The `self-que[ring`
navbar](https://python.langchain.com/docs/modules/data_connection/retrievers/self_query/)
has repeated `self-quering` repeated in each menu item. I've simplified
it to be more readable
- removed `self-quering` from a title of each page;
- added description to the vector stores
- added description and link to the Integration Card
(`integrations/providers`) of the vector stores when they are missed.
- Description: Adding support for self-querying to Vectara integration
- Issue: per customer request
- Tag maintainer: @rlancemartin @baskaryan
- Twitter handle: @ofermend
Also updated some documentation, added self-query testing, and a demo
notebook with self-query example.
