[Doc] Fix broken links

Author: fzaninotto

docs/AppTheme.md

@@ -108,7 +108,7 @@ const App = () => (
 
 React-admin comes with 5 built-in themes, each one having a light and a dark variant. You can use them as a starting point for your custom theme, or use them as-is.
 
-|    [Default](#default) [![Default light theme](./img/defaultLightTheme1.jpg)]((#default)) |    [B&W](#bw) [![B&W light theme](./img/bwLightTheme1.jpg)](#bw) |
+|    [Default](#default) [![Default light theme](./img/defaultLightTheme1.jpg)](#default) |    [B&W](#bw) [![B&W light theme](./img/bwLightTheme1.jpg)](#bw) |
 |    [Nano](#nano) [![Nano light theme](./img/nanoLightTheme1.jpg)](#nano) |    [Radiant](#radiant) [![Radiant light theme](./img/radiantLightTheme1.jpg)](#radiant) |
 |    [House](#house) [![House light theme](./img/houseLightTheme1.jpg)](#house) |
 

docs/Theming.md

@@ -121,9 +121,9 @@ const App = () => (
 
 React-admin comes with 5 built-in themes:
 
-|    [Default](./AppTheme.md#default) [![Default light theme](./img/defaultLightTheme1.jpg)]((#default)) |    [B&W](./AppTheme.md#bw) [![B&W light theme](./img/bwLightTheme1.jpg)](./AppTheme.md#bw) |
-|    [Nano](./AppTheme.md#nano) [![Nano light theme](./img/nanoLightTheme1.jpg)](./AppTheme.md#nano) |    [Radiant](./AppTheme.md#radiant) [![Radiant light theme](./img/radiantLightTheme1.jpg)](./AppTheme.md#radiant) |
-|    [House](./AppTheme.md#house) [![House light theme](./img/houseLightTheme1.jpg)](./AppTheme.md#house) |
+|    [Default](./AppTheme.md#default) [![Default light theme](./img/defaultLightTheme1.jpg)]((AppTheme.html#default)) |    [B&W](./AppTheme.md#bw) [![B&W light theme](./img/bwLightTheme1.jpg)](./AppTheme.html#bw) |
+|    [Nano](./AppTheme.md#nano) [![Nano light theme](./img/nanoLightTheme1.jpg)](./AppTheme.html#nano) |    [Radiant](./AppTheme.md#radiant) [![Radiant light theme](./img/radiantLightTheme1.jpg)](./AppTheme.html#radiant) |
+|    [House](./AppTheme.md#house) [![House light theme](./img/houseLightTheme1.jpg)](./AppTheme.html#house) |
 
 The [e-commerce demo](https://marmelab.com/react-admin-demo/) contains a theme switcher, so you can test them in a real application.