documentaions for enabling new providers

[rajabhupati]

Describe the feature you'd like
Enabling new llm providers and custom providers

Additional context
Everyday we see new providers getting onboarded to llm space like azure aws bedrock and recently databricks . It will be difficult to add each one of them but can we create documentation to help users to create their providers and using into flow

[HenryHengZJ]

we have a PR that would allow users to create community plugin, will be working on it to bring this live