website: make the About section properly bilingual

The About pages (Donate/Copyright/Acknowledgements) always rendered with
Chinese chrome regardless of the reader's language, and Acknowledgements
stacked English on top of Chinese. An English reader reached them from the
English menu and got a Chinese page.

Introduce an 'about-en' page type (the theme's 'type' field selects both
menu language and which section's table-of-contents to list, so a separate
type is the clean way to split). Route the shared partials -- header, page,
sidebar, layout -- through a single isEn = book-en-us || about-en helper.
Add English About pages under /about/en/, point the English menu and the
English book footer at them, and reduce each Chinese About page to Chinese
only. donate.md becomes a committed source file (was generated from
assets/, which stays bilingual for the GitHub README), so it drops out of
the Makefile copy/clean and .gitignore.

Author: changkun

.gitignore

@@ -40,7 +40,6 @@ website/src/modern-cpp/zh-cn/*
 website/src/modern-cpp/en-us/*
 website/src/modern-cpp/exercises
 website/src/modern-cpp/code
-website/src/modern-cpp/about/donate.md
 website/src/modern-cpp/assets/alipay.jpg
 website/src/modern-cpp/assets/cover-2nd-en.png
 website/src/modern-cpp/assets/cover-2nd.png

website/Makefile

@@ -7,7 +7,6 @@ all: clean
 	cp ../assets/cover-2nd-en-logo.png ./src/modern-cpp/assets/cover-2nd-en-logo.png
 	cp ../assets/alipay.jpg ./src/modern-cpp/assets/alipay.jpg
 	cp ../assets/wechat.jpg ./src/modern-cpp/assets/wechat.jpg
-	cp ../assets/donate.md ./src/modern-cpp/about/
 	cp -r ../assets/figures ./src/modern-cpp/assets/figures
 	cp -r ../exercises ./src/modern-cpp/
 	cp -r ../code ./src/modern-cpp/
@@ -23,7 +22,6 @@ clean:
 		./src/modern-cpp/assets/figures \
 		./src/modern-cpp/assets/alipay.jpg \
 		./src/modern-cpp/assets/wechat.jpg \
-		./src/modern-cpp/about/donate.md \
 		./src/modern-cpp/code \
 		./src/modern-cpp/exercises \
 		public db.json src/modern-cpp/zh-cn src/modern-cpp/en-us

website/src/modern-cpp/about/ack.md

@@ -4,14 +4,6 @@ type: about
 order: 4
 ---
 
-## Acknowledgements
-
-This book was originally written in Chinese by [Changkun Ou](https://changkun.de).
-
-The author has limited time and language skills. If readers find any mistakes in the book or any language improvements, please feel free to open an [Issue](https://github.com/changkun/modern-cpp-tutorial/issues) or start a [Pull request](https://github.com/changkun/modern-cpp-tutorial/pulls). For detailed guidelines and checklist, please refer to [How to contribute](CONTRIBUTING.md).
-
-The author is grateful to all contributors, including but not limited to [Contributors](https://github.com/changkun/modern-cpp-tutorial/graphs/contributors).
-
 ## 致谢
 
-笔者时间和水平有限，如果读者发现书中内容的错误，欢迎提 [Issue](https://github.com/changkun/modern-cpp-tutorial/issues)，或者直接提 [Pull request](https://github.com/changkun/modern-cpp-tutorial/pulls)。详细贡献指南请参考[如何参与贡献](CONTRIBUTING.md)，由衷感谢每一位指出本书中出现错误的读者，包括但不限于 [Contributors](https://github.com/changkun/modern-cpp-tutorial/graphs/contributors)。
+笔者时间和水平有限，如果读者发现书中内容的错误，欢迎提 [Issue](https://github.com/changkun/modern-cpp-tutorial/issues)，或者直接提 [Pull request](https://github.com/changkun/modern-cpp-tutorial/pulls)。详细贡献指南请参考[如何参与贡献](https://github.com/changkun/modern-cpp-tutorial/blob/master/CONTRIBUTING.md)，由衷感谢每一位指出本书中出现错误的读者，包括但不限于 [Contributors](https://github.com/changkun/modern-cpp-tutorial/graphs/contributors)。

website/src/modern-cpp/about/donate.md

@@ -0,0 +1,17 @@
+---
+title: 资助
+type: about
+order: 1
+---
+
+## 资助
+
+如果你认为本书对你起到了帮助，并希望赞助作者，可以通过下面的二维码给予支持：
+
+|微信|支付宝|
+|:--:|:--:|
+|![](../assets/wechat.jpg) | ![](../assets/alipay.jpg)|
+
+你也可以通过 PayPal 资助：
+
+[![](https://img.shields.io/badge/donate-PayPal-104098.svg?style=popout-square&logo=PayPal)](https://www.paypal.me/changkunde/4.99eur)

website/src/modern-cpp/about/en/ack.md

@@ -0,0 +1,13 @@
+---
+title: Acknowledgements
+type: about-en
+order: 4
+---
+
+## Acknowledgements
+
+This book was originally written in Chinese by [Changkun Ou](https://changkun.de).
+
+The author has limited time and language skills. If readers find any mistakes in the book or any language improvements, please feel free to open an [Issue](https://github.com/changkun/modern-cpp-tutorial/issues) or start a [Pull request](https://github.com/changkun/modern-cpp-tutorial/pulls). For detailed guidelines and checklist, please refer to [How to contribute](https://github.com/changkun/modern-cpp-tutorial/blob/master/CONTRIBUTING.md).
+
+The author is grateful to all contributors, including but not limited to [Contributors](https://github.com/changkun/modern-cpp-tutorial/graphs/contributors).

website/src/modern-cpp/about/en/copyright.md

@@ -0,0 +1,9 @@
+---
+title: Copyright
+type: about-en
+order: 3
+---
+
+<a rel="license" href="https://creativecommons.org/licenses/by-nc-nd/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-nc-nd/4.0/80x15.png" /></a>
+
+This book is written by [Changkun Ou](https://github.com/changkun) and licensed under the [Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License](https://creativecommons.org/licenses/by-nc-nd/4.0/). The code in this project is open sourced under the [MIT](https://opensource.org/licenses/MIT) license.

website/src/modern-cpp/about/en/donate.md

@@ -0,0 +1,17 @@
+---
+title: Donate
+type: about-en
+order: 1
+---
+
+## Donate
+
+I would love it if you support me to make the book better:
+
+[![](https://img.shields.io/badge/donate-PayPal-104098.svg?style=popout-square&logo=PayPal)](https://www.paypal.me/changkunde/4.99eur)
+
+If you are in mainland China, you can also support via WeChat or AliPay:
+
+|WeChat|AliPay|
+|:--:|:--:|
+|![](../../assets/wechat.jpg) | ![](../../assets/alipay.jpg)|

website/themes/moderncpp/layout/page.ejs

@@ -1,9 +1,10 @@
+<% var isEn = page.type == 'book-en-us' || page.type == 'about-en' %>
 <% if (page.type) { %>
   <%- partial('partials/sidebar', { type: page.type, index: page.index }) %>
 <% } else { %>
   <div class="sidebar">
     <ul class="main-menu">
-        <% if (page.type == 'book-en-us') { %>
+        <% if (isEn) { %>
           <%- partial('partials/main_menu_en', { context: 'nav' }) %>
         <% } else {%>
           <%- partial('partials/main_menu', { context: 'nav' }) %>
@@ -22,14 +23,14 @@
     <% }) %>
   </div>
 
-  <% if (page.type == 'book-en-us') { %>
+  <% if (isEn) { %>
     <div class="footer">
         <p>
           <a href="https://changkun.de">Changkun Ou</a> &copy; 2016-<%- new Date().getFullYear() %>.
           The book is licensed under <a rel="license" href="https://creativecommons.org/licenses/by-nc-nd/4.0/">Creative Commons Attribution-NonCommercial-NoDerivatives 4.0</a>, code is open sourced under the <a href="https://opensource.org/licenses/MIT" target="_blank">MIT</a> License. </a>
         </p>
         <p>
-          If you like the book, you could <a href="/modern-cpp/about/donate.html">donate the author</a>.
+          If you like the book, you could <a href="/modern-cpp/about/en/donate.html">donate the author</a>.
         </p>
       </div>
   <% } else {%>

website/themes/moderncpp/layout/partials/header.ejs

@@ -1,6 +1,7 @@
+<% var isEn = page.type == 'book-en-us' || page.type == 'about-en' %>
 <div id="header">
   <a id="logo" href="<%- url_for("/modern-cpp/") %>">
-    <% if (page.type == 'book-en-us') { %>
+    <% if (isEn) { %>
       <img src="<%- url_for("/modern-cpp/assets/cover-2nd-en-logo.png") %>">
       <span>Modern C++ Tutorial: C++11 to C++26 On the Fly</span>
     <% } else {%>
@@ -9,7 +10,7 @@
     <% } %>
   </a>
   <ul id="nav">
-    <% if (page.type == 'book-en-us') { %>
+    <% if (isEn) { %>
       <%- partial('partials/main_menu_en', { context: 'nav' }) %>
     <% } else {%>
       <%- partial('partials/main_menu', { context: 'nav' }) %>

website/themes/moderncpp/layout/partials/main_menu_en.ejs

@@ -15,9 +15,9 @@
 <a class="nav-link">About</a><span class="arrow"></span>
 <ul class="nav-dropdown">
     <li><ul>
-    <li><a class="nav-link" href="<%- url_for("/modern-cpp/about/donate.html") %>" >Donate</a></li>
-    <li><a class="nav-link" href="<%- url_for("/modern-cpp/about/copyright.html") %>" >Copyright</a></li>
-    <li><a class="nav-link" href="<%- url_for("/modern-cpp/about/ack.html") %>" >Acknowledgements</a></li>
+    <li><a class="nav-link" href="<%- url_for("/modern-cpp/about/en/donate.html") %>" >Donate</a></li>
+    <li><a class="nav-link" href="<%- url_for("/modern-cpp/about/en/copyright.html") %>" >Copyright</a></li>
+    <li><a class="nav-link" href="<%- url_for("/modern-cpp/about/en/ack.html") %>" >Acknowledgements</a></li>
     </ul></li>
 </ul>
 </li>