[GH-1764] Document Spark Connect server setup

[zhangxinyao88]

Did you read the Contributor Guide?

• Yes, I have read the Contributor Rules and Contributor Development Guide.

Is this PR related to a ticket?

• Yes. Closes Are Apache Sedona geometry functions compatible with Spark Connect? #1764.

What changes were proposed in this PR?

• Document how to start a Spark Connect server with the required Sedona packages, Kryo registrator, and SQL extension.
• Explain how the package coordinates differ between Spark 3.5 and Spark 4.0 or later.
• Add a small Python example that connects to the server and runs a Sedona SQL function.

How was this patch tested?

• Ran all applicable pre-commit hooks for docs/setup/cluster.md.
• Built the documentation successfully with uv run mkdocs build.
• Verified the rendered section, links, version macros, and code examples.

Did this PR include necessary documentation updates?

• Yes, this PR is a documentation update.

[jiayuasu]

Thank you!