Improving the contirbution doc to add more LLM, readers and vectorStore support

[himself65]

There are many packages on the Python side; we missed tons of them for the typescript side.

We must improve the document and solid types to let people understand how to contribute to LlamaIndexTS.

feedback from @jerryjliu

Related

• Support for AWS Bedrock? #736
• strong typing for LlamaIndexTS #739
• Add support for HuggingFace LLM Inference  #686
• NLSQLTableQueryEngine alternavite in TS #573
• [Feature Req] Gemini Pro API Support #286
• Feature request: DiscordReader #264
• Add support for Perplexity API #227
• MongoDocumentStore on TS #136
• Add support for supabase vector store #32

[himself65]

There is some progress on this thread. For the recent PRs, I was moving some modules into @llamaindex/core with no extra dependency, so It will be easy to extend.

[himself65]

Note that we are moving the document to next.js (fumadoc).