gh-35069: Conform to doc requirements so that the docs look more beautiful
These are mostly either of the form of unindenting text that was
accidentally put in a code block, or correctly adding `::` or
`EXAMPLES::` so that docs render nicely.
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URL: https://github.com/sagemath/sage/pull/35069
Reported by: Alex J Best
Reviewer(s): Alex J Best, Frédéric Chapoton, Travis Scrimshaw
