docs: Add documentation on how to contribute a Vector DB provider and

updated Test documentation and added a shortcut

Signed-off-by: Francisco Javier Arceo <farceo@redhat.com>

docs/source/contributing/index.md

@@ -2,14 +2,28 @@
 ```{include} ../../../CONTRIBUTING.md
 ```
 
-See the [Adding a New API Provider](new_api_provider.md) which describes how to add new API providers to the Stack.
+## Testing
 
+See the [Test Page](testing.md) which describes how to test your changes.
+```{toctree}
+:maxdepth: 1
+:hidden:
+:caption: Testing
 
+testing
+```
 
+## Adding a New Provider
+
+See the [Adding a New API Provider Page](new_api_provider.md) which describes how to add new API providers to the Stack.
+
+See the [Vector Database Page](new_vector_database.md) which describes how to add a new vector databases with Llama Stack.
+
+See the [External Provider Page](../providers/external/index.md) which describes how to add external providers to the Stack.
 ```{toctree}
 :maxdepth: 1
 :hidden:
 
 new_api_provider
-testing
+new_vector_database
 ```