Rich text editing fields

## As a content editor I want to limit or control formatting in a rich text box so that I can easily maintain consistency of header use and formatting on the pages I manage.

### to do

- [ ] Look across all instances of rich text fields in Joplin and make sure they align/correspond to content type need
- [ ] Special attention to heading display (if you use heading in rich text, displays consistently on Janis)

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### background

Let's revisit WYSIWYG rich text options in Joplin. WYSIWYGs may function differently on different content blocks—for example, the one for steps on a service page vs. additional information on a service page. Let's define what's needed where.

Some things to consider:
- Which heading levels should be there? Which shouldn't?
- Let's get rid of H1! #3182
- See also #1257 re: semantic HTML
- We have implemented the ability to add code (markdown/HTML) in certain blocks to achieve MVP functionality. Ideally, in the future, a content editor wouldn't need to do that. Let's document where that's happened and make tech debt issues to address in the future.
- Resolve #2368 department placeholder stuff

**Old notes**
Remove H4 and ol, see https://docs.google.com/spreadsheets/d/1ZkH93F4tJ0_Zjx4t8k6k6TgwSlOh8u8ejWmegE6WqH0/edit?ts=5c3e0a70#gid=1232003425