Markdown shortcuts for bold, italic, and insert link

What does this MR do?

Partial completion of #17181

Screenshots

Screen_Recording_2020-04-29_at_5.29.17_pm

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content