Polish manual tagged APIs

[Wumpf]

• python how has described for component batches
• C++ can infer descriptor for explicit component batch/column creation
• some snippet niceifications for Rust

[github-actions]

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Result	Commit	Link	Manifest
✅	aac1afd	https://rerun.io/viewer/pr/8869	+nightly +main

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[teh-cmc]

Snippets all pass locally -- I'm just waiting for the CI to make sure the C++ changes are valid on all platforms...