Add simple WYSIWYG editor for exercise descriptions #189

[sandimilohanic]

Proposed Changes

Related Issues (if applicable)

Please check that the PR fulfills these requirements

• [ ] Set a 100 character limit in your editor/IDE to avoid white space diffs in the PR
• [ ] Tests for the changes have been added (for bug fixes / features)
• [ ] Added yourself to AUTHORS.md

[rolandgeider]

mhhh, I can't seem to activate the editor