Adding available shortcut functions to the documentation
In several sections of the documentation, all the shortcut functions that can be used is listed.
https://git.pwmt.org/pwmt/zathura/-/blob/develop/doc/man/zathurarc.5.rst#map-mapping-a-shortcut ("Shortcut functions" session)
https://git.pwmt.org/pwmt/zathura/-/blob/develop/doc/configuration/map.rst#shortcut-functions
However, it appears that many shortcut functions are not listed in the documentation. The complete list should be in https://git.pwmt.org/pwmt/zathura/-/blob/develop/zathura/config.c#L537-567 .
As an aside, it would be useful to list the shortcut function along with what's the default keybinding for it as well.