Get a simple toolbar to help format a markdown cell

[laurentperrinet]

It would be quite practical (especially for newbies) to have some help when formatting a markdown cell - such as when I am editing this comment within github's issue system:

The "preview" tab is not necessary (a command-enter would render the code) but other icons are useful shortcuts to include URLs, lists or code...

[foice]

very surprised nothing like this exists in extensions... did I miss it?