docs: fix README.md 404 when navigate from .github/

Author: diyews

.github/README-es.md

@@ -1,7 +1,7 @@
 <div align="center">
   <a href="https://nostalgic-css.github.io/NES.css/" target="_blank"><img src="https://user-images.githubusercontent.com/5305599/49061716-da649680-f254-11e8-9a89-d95a7407ec6a.png" alt="NES.css: NES-style  CSS framework" style="max-width: 100%;" width="600" height="315"></a>
 
-  <a href="README.md">English</a> / <a href=".github/README-jp.md">日本語</a> / <a href="README-zh-CN.md">简体中文</a> / <a href=".github/README-pt-BR.md">Português</a>　/ <a href=".github/README-ru.md">Русский</a>
+  <a href="/README.md">English</a> / <a href=".github/README-jp.md">日本語</a> / <a href="README-zh-CN.md">简体中文</a> / <a href=".github/README-pt-BR.md">Português</a>　/ <a href=".github/README-ru.md">Русский</a>
 </div>
 
 NES.css es un **NES-style(8bit-like)** CSS Framework.

.github/README-jp.md

@@ -1,7 +1,7 @@
 <div align="center">
   <a href="https://nostalgic-css.github.io/NES.css/" target="_blank"><img src="https://user-images.githubusercontent.com/5305599/49061716-da649680-f254-11e8-9a89-d95a7407ec6a.png" alt="NES.css: NES-style  CSS framework" style="max-width: 100%;" width="600" height="315"></a>
 
-  <a href="README.md">English</a> / <a href="README-zh-CN.md">简体中文</a> / <a href="README-es.md">Español</a> / <a href="README-pt-BR.md">Português</a>　/ <a href=".github/README-ru.md">Русский</a>
+  <a href="/README.md">English</a> / <a href="README-zh-CN.md">简体中文</a> / <a href="README-es.md">Español</a> / <a href="README-pt-BR.md">Português</a>　/ <a href=".github/README-ru.md">Русский</a>
 </div>
 
 NES.cssは **ファミコン風(8bit ライク)** なCSSフレームワークです。

.github/README-pt-BR.md

@@ -1,7 +1,7 @@
 <div align="center">
   <a href="https://nostalgic-css.github.io/NES.css/" target="_blank"><img src="https://user-images.githubusercontent.com/5305599/49061716-da649680-f254-11e8-9a89-d95a7407ec6a.png" alt="NES.css: NES-style  CSS framework" style="max-width: 100%;" width="600" height="315"></a>
 
-  <a href="README.md">English</a> / <a href=".github/README-jp.md">日本語</a> / <a href="README-zh-CN.md">简体中文</a> / <a href=".github/README-es.md">Español</a>　/ <a href=".github/README-ru.md">Русский</a>
+  <a href="/README.md">English</a> / <a href=".github/README-jp.md">日本語</a> / <a href="README-zh-CN.md">简体中文</a> / <a href=".github/README-es.md">Español</a>　/ <a href=".github/README-ru.md">Русский</a>
 </div>
 
 NES.css é um Framework CSS, no **estilo NES(8bit)**.

.github/README-ru.md

@@ -1,7 +1,7 @@
 <div align="center">
   <a href="https://nostalgic-css.github.io/NES.css/" target="_blank"><img src="https://user-images.githubusercontent.com/5305599/49061716-da649680-f254-11e8-9a89-d95a7407ec6a.png" alt="NES.css: NES-style  CSS framework" style="max-width: 100%;" width="600" height="315"></a>
 
-  <a href="README.md">English</a> / <a href=".github/README-jp.md">日本語</a> / <a href="README-zh-CN.md">简体中文</a> / <a href=".github/README-pt-BR.md">Português</a>
+  <a href="/README.md">English</a> / <a href=".github/README-jp.md">日本語</a> / <a href="README-zh-CN.md">简体中文</a> / <a href=".github/README-pt-BR.md">Português</a>
 </div>
 
 NES.css - это CSS фреймворк в стиле **NES(8bit)**

.github/README-zh-CN.md

@@ -1,7 +1,7 @@
 <div align="center">
   <a href="https://nostalgic-css.github.io/NES.css/" target="_blank"><img src="https://user-images.githubusercontent.com/5305599/49061716-da649680-f254-11e8-9a89-d95a7407ec6a.png" alt="NES.css: NES-style  CSS framework" style="max-width:100%;" width="600" height="315"></a>
 
-  <a href="README.md">English</a> / <a href="README-jp.md">日本語</a> / <a href="README-es.md">Español</a> / <a href="README-pt-BR.md">Português</a>　/ <a href=".github/README-ru.md">Русский</a>
+  <a href="/README.md">English</a> / <a href="README-jp.md">日本語</a> / <a href="README-es.md">Español</a> / <a href="README-pt-BR.md">Português</a>　/ <a href=".github/README-ru.md">Русский</a>
 </div>
 
 NES.css 是一款 **NES-风格(8位机)** 的CSS 框架.