add support for `-mc` to conc.alias

[TheReverendB]

Start Druid Starry Form Dragon. A constellation of a wise dragon appears on you. When you make an Intelligence or a Wisdom check or a Constitution saving throw to maintain concentration on a spell, you can treat a roll of 9 or lower on the d20 as a 10.

What Alias/Snippet is this for?

Summary

adding -mc support for !conc

Checklist

PR Type

• [ ] This PR is a code change that implements a feature request.
• [ ] This PR fixes an issue.
• [x] This PR adds a new feature that is not an open feature request.
• [ ] This PR is not a code change (e.g. documentation, README, ...)

  Other

• [ ] This PR is a breaking change (e.g. methods or parameters removed/renamed)
• [x] If code changes were made then they have been tested.
• [x] I have updated the documentation to reflect the changes.
• [ ] I properly commented my code where appropriate

[TheReverendB]

Adjusted code and tested on self and target saves. Updated the markdown to reflect the changes.