inApp Keyboard Shortcuts cheat sheet

keyboard shortcuts are already documented in deltachat-desktop/ at master · deltachat/deltachat-desktop · GitHub, but that is impossible to find for normal users.

So I propose an inApp keybindings cheatsheet accessible from the Help menu and via common keyboard shortcut.

for reference: discord already has sth. like that:

This addition would make the knowledge about the keyboard shortcuts more accessible for users of deltachat desktop.