Fix two links

- fix valkey documentation link to point to index.md taking user to main docs site
- fix 2 Extensions links to take user to modules intro and then check the available modules api.

Signed-off-by: Dragos Andriciuc <[email protected]>

Author: Andriciuc

topics/data-types.md

@@ -108,4 +108,4 @@ For more information, see:
 To extend the features provided by the included data types, use one of these options:
 
 1. Write your own custom [server-side functions in Lua](programmability.md).
-2. Write your own Valkey module using the [modules API](modules-intro.md) or check out the [modules](../modules/).
+2. Write your own Valkey module using [Modules Introduction](modules-intro.md) or check out the available [modules](modules-api-ref.md).

topics/server.md

@@ -78,4 +78,4 @@ the config file:
 
 ## See also
 
-[Valkey documentation](./), [Introduction](introduction.md), [Configuration](valkey.conf.md), [Installation](installation.md), [valkey-cli](cli.md)
+[Valkey documentation](index.md), [Introduction](introduction.md), [Configuration](valkey.conf.md), [Installation](installation.md), [valkey-cli](cli.md)