Showing actual git command for key bindings in menu

**Is your feature request related to a problem? Please describe.**
The `menu` (i.e. pressing `x`) is really helpful, but it doesn't show the actual git command for a given key binding and what is going to happen when executing. For instance, it is not clear what the `d` (delete commit) actually does and led to a related #2426 issue. I know that the command Log does show the commands but only after executing the command and not before.

**Describe the solution you'd like**
Showing the actual git command when selecting an entry in the menu. I.e. after pressing `x` and going down to `d delete commit` in the commit window, it should show somewhere what is going to happen. On top of the git log ideally even an intuitive explanation, typical application or even a link.

**Describe alternatives you've considered**
An alternative would we to have a text/help file with mapping - command association. I couldn't find that in the code base either however.