[WIP] mini markdown cheatsheet by comment form

[mariocsee]

What type of PR is this? (check all applicable)

• Feature

Description

Adds a hidden section near the comment input for same window markdown cheatsheet. Clicking the info button opens and closes the section.

Still deciding whether to put the editor guide (/p/editor_guide) or markdown guide (https://github.com/adam-p/markdown-here/wiki/Markdown-Here-Cheatsheet) in a scroll view or have a more condensed markdown cheatsheet designed with a link to the editor guide or markdown cheatsheet if the user needs a more detailed guide.

Update:
When textarea is in focus, the markdown hints appear—just like Slack.
When you click on the Markdown button to the right of image upload, the section below with more markdown details shows. (more shortcuts can be added)
Not sure whether to use one or both.
The cheatsheet pushes the comment section down a little, but can also be made to appear on top of the first comment.

Related Tickets & Documents

Resolves #49

Mobile & Desktop Screenshots/Recordings (if there are UI changes)

Added to documentation?

• no documentation needed

[omenking]

I think what I would want here is liquid tags since I always have to hunt those down.
For me, this is more useful in writing a post than writing in comments.

[mariocsee]

Will revisit in the future.