help-overlay: Use action names directly
Some things I noticed:
- I was not able to find the actions for "Next Tab" and "Previous Tab"
- Naturally it is not possible to use this for the bindings of "Switch to Tab"
- The menu does not include shortcuts for showing the help overlay (this might or might not be a good idea)
- There is no Control-Q (Control-W) binding for closing the app (window)