Use more consistent formatting in Rust docs

[gpeacock]

Eric has requested a blank line between the intro and header sections in the comments blocks to make them more readable in Rust. This does not impact the generated docs since they will always add space there.

When we want a title section to stand alone on a comment, we should also add a blank line after the title. Docs will wrap all the lines together unless you add a blank line in the comments.

We also need to update lots of docs, but that's probably another issue.

[github-jira-sync-bot]

:white_check_mark: Jira issue https://jira.corp.adobe.com/browse/CAI-10473 is successfully created for this GitHub issue.