DOC-13644: [Capella] Vector-index sample bucket

[simon-dew]

Docs issue: DOC-13644

For Capella only:

• Updates the name of the vector-sample bucket to color-vector-sample
• Adds instructions to import rgb-questions, which is not included by default
• Updates queries with USE KEYS to avoid creating primary indexes unless absolutely necessary — Query without Indexes is not available by default for paid service plans
• Updates some existing queries using the rgb collection, because the ID for each document has no # at the start, unlike when you import fromcolor_data_2vectors.zip

Document previews:

• Vector Search Using Hyperscale Vector Indexes › Examples on this Page
• Filtered Search Using Composite Vector Indexes › Examples on this Page

... and many others, these are just the pages with the most changes.

You will need the Docs Team credentials on Confluence.

[sarahlwelton]

I can still pop back on to approve this if you want it to go in today, but we need to fix this part.