docs: part 1 - fix warnings in documentation generation (#2861)

**Description**
This PR removes some of the warnings when uv builds the docs
- Errors appear when generating docs about .md files not appearing in
toctree. ~~Adding content to the `providers-gen.py ` file that adds `---
orphan: true ---` to to each file.~~. Added a toctree generator to the
`providers-gen.py` file, this gets rid of the errors in the builds.
- Deletes the `_openai_compat` files, extension of PR #2849
- Adds the `files` APIs section to the `providers` toctree on the index
page
- Manually adds the `--- orphan: true ---` to the advanced apis. Ill try
to find a way to modify the providers code gen so it automatically adds
it, but this fixes the errors.
- Adds the `testing.md` to the `contributing` toctree
- Adds `starting_llama_stack_server.md` to `distributions` toctree

There are some other warnings im still looking at but this PR gets rid
of most of the toctree errors
Theres also an issue with the actual distribution-codegen that I can
investigate in another PR. Opened a bug for it here #2873

docs/source/providers/vector_io/index.md

@@ -1,16 +1,24 @@
-# Vector_Io Providers
+# Vector_Io 
+
+## Overview
 
 This section contains documentation for all available providers for the **vector_io** API.
 
-- [inline::chromadb](inline_chromadb.md)
-- [inline::faiss](inline_faiss.md)
-- [inline::meta-reference](inline_meta-reference.md)
-- [inline::milvus](inline_milvus.md)
-- [inline::qdrant](inline_qdrant.md)
-- [inline::sqlite-vec](inline_sqlite-vec.md)
-- [inline::sqlite_vec](inline_sqlite_vec.md)
-- [remote::chromadb](remote_chromadb.md)
-- [remote::milvus](remote_milvus.md)
-- [remote::pgvector](remote_pgvector.md)
-- [remote::qdrant](remote_qdrant.md)
-- [remote::weaviate](remote_weaviate.md)
+## Providers
+
+```{toctree}
+:maxdepth: 1
+
+inline_chromadb
+inline_faiss
+inline_meta-reference
+inline_milvus
+inline_qdrant
+inline_sqlite-vec
+inline_sqlite_vec
+remote_chromadb
+remote_milvus
+remote_pgvector
+remote_qdrant
+remote_weaviate
+```