* first commit for the Astra DB / Cassandra notebooks
* add json with quotes
* towards the final cassIO pilot notebook
* small changes to the copy
* cassIO pilot completed and its readme done
* fix silly markdown error
* fix silly markdown error 2
* astra vector link change and vector search picture improved
* added link to docs for connecting to Cassandra cluster
* CQL version of the flow
* revised readme
* final adjustments around metrics/distances
* links' final version assumes files in openai's main branch
* Add ref to QA+vector general guide; fix prompt; clarified conclusion paragraph; typos
