[FIX] Update LlamaIndex links

[l145dev]

Description of changes

closes #4446

• Change link for vector store page to point to correct link on LlamaIndex

• Change link of demo Jupyter notebook file to point to correct place in LlamaIndex repository

• Improvements & Bug fixes

  • LlamaIndex link fixes

• New functionality

  • /

Test plan

Open link in a tab and see a non-404 page

• [ ] Tests pass locally with pytest for python, yarn test for js, cargo test for rust

Migration plan

No

Observability plan

Open the link in a browser

Documentation Changes

No