Make the docs overview page as the main docs landing page

- Make the docs overview page available at docs.khoj.dev root instead of
under docs.khoj.dev/docs path
  - Remove the new landing page, it is unnecessary.
- Remove /docs path prefix from links to internal doc pages
- Remove .md path suffix in internal doc pages for consistency

documentation/docs/clients/emacs.md

@@ -87,13 +87,13 @@ M-x package-install khoj
 
 ## Use
 ### Search
-See [Khoj Search](/features/search.md) for details
+See [Khoj Search](/features/search) for details
 1. Hit  `C-c s s` (or `M-x khoj RET s`) to open khoj search
 2. Enter your query in natural language<br/>
   E.g *"What is the meaning of life?"*, *"My life goals for 2023"*
 
 ### Chat
-See [Khoj Chat](/features/chat.md) for details
+See [Khoj Chat](/features/chat) for details
 1. Hit `C-c s c` (or `M-x khoj RET c`) to open khoj chat
 2. Ask questions in a natural, conversational style<br/>
   E.g *"When did I file my taxes last year?"*