Docs: Add FLOAT_VECTOR overview example

[nightcityblade]

Supersedes #297, which GitHub automatically closed after its source branch history was accidentally rewritten during follow-up. This replacement is rebuilt as one commit from current main and includes the requested review updates.

Fixes #190

Adds a focused FloatVector example to the feature overview showing how to define an embedding column, store a vector, and build a knn_match query. It also links to the complete vector guide and updates the extension-type introduction so it no longer implies the dialect has only two extension types.

Testing

• make html (passed)
• make linkcheck (the new internal cross-reference passes; the command remains nonzero on two unrelated pre-existing GitHub URLs returning 404)
• git diff --check (passed)

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on this repository. Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 01bf5f10-05eb-4ec8-94be-a7baf4b532e0

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[florinutz]

Thank you!

The extra, the refresh, and the vector-type anchor all look right, and I confirmed the example returns [('example',)] against a live CrateDB. One thing left from my "link to its anchor" comment: I meant the type table in docs/data-types.rst. The float_vector row is still the only extension type there that isn't clickable: could you make it match the others?

[nightcityblade]

Addressed in 767ac12: the FloatVector row in the type table now links to the existing FloatVector anchor and is labeled consistently with the other extension types. Documentation HTML build and linkcheck both pass.

[bgunebakan]

Thank you, look like @florinutz comments already addressed with your last commit.