Improve quality scale documentation

[CoMPaTech]

Willing to put forward a PR to solve this, just noting down findings while in the quality scale process with @joostlek

• integration-quality-scale/#keeping-track-of-the-implemented-rules improve first-time use (e.g. hint at - and _
• integration-quality-scale/rules/exception-translations doesn't yield message as required key - Align exception-translations with translation requirements #2487

[CoMPaTech]

@joostlek for the improved first time - thinking out loud - would adding the - vs _ as a small remark on https://developers.home-assistant.io/docs/core/integration-quality-scale/#keeping-track-of-the-implemented-rules work? I'd also suggest just having an example file there (or on the checklist page) that has all currently known rules with todo.

Or just split the Checklist into 4 sections, each with both the markdown checklist for a PR + accompanying example of the rules-yaml?