add !help command to output a compact readme file to the user

As documentation is key, the user should be able to get some simple instructions of how to use the commands. A designated !help along with the actual instruction could be used to aquire information for how to use the tickbar, how to use the rolling function etc.

Start by locating the existing Java handling for commands beginning with ! and the command behavior for tickbar and rolling. Add a !help entry that gives users compact instructions for those commands, then verify that invoking !help displays the intended guidance.

Written by the indexing model from the issue text.