docs: add vectorstore docs (#22)

* docs: add vectorstore docs

* Update docs/vector_store.ipynb

Co-authored-by: Jack Wotherspoon <jackwoth@google.com>

* Update docs/vector_store.ipynb

Co-authored-by: Jack Wotherspoon <jackwoth@google.com>

* Update docs/vector_store.ipynb

Co-authored-by: Jack Wotherspoon <jackwoth@google.com>

* Update docs/vector_store.ipynb

Co-authored-by: Jack Wotherspoon <jackwoth@google.com>

* update

* Update

* Update docs/vector_store.ipynb

Co-authored-by: Jack Wotherspoon <jackwoth@google.com>

* Update docs/vector_store.ipynb

Co-authored-by: Jack Wotherspoon <jackwoth@google.com>

* update

* rename

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Co-authored-by: Jack Wotherspoon <jackwoth@google.com>