UI: Improve clarity and details of the 'help' command output

[tecnolgd]

• The help message printed by cmdHandler() inside src/core/command_handler.cpp seems to misguide or provide partial knowledge on how to use the commands such as in shortcut add or history goto.

[abhinav25005229-creator]

Hi! I'd like to work on this issue. Could you please assign it to me if it's still available?