Message user with helpful information after role update

[Errolyn]

Bot messages user with information on how to sign up for roles and set pronouns

Welcome message:

Thanks for accepting the Code of Conduct! In our <#bot-speak-ID> channel you can sign up for different roles to get notifications based on things you are interested in, you can also set your pronouns all with the command ?rank [rankName]. To see the available ranks, use ?ranks. Have fun and let a mod know if you have any questions!

parent issue #11