forum guidelines/rules 2nd draft review

Hi again,
        I made the edits requested from the first review.  And those gave me 
some other thoughts.  I added a couple of new "wrinkles" to the prerequisites 
for moderator section, and for the duties and responsibilities.

        For the change in prerequisites, I thought it couldn't hurt to encourage 
wider participation in the community, just by adding that language, but it's not 
a strict prerequisite.

        For duties and responsibilities, the ability for a moderator to choose 
what they want to moderate is already allowed for the gallery moderation.  So 
that's not a stretch.  The reason for adding it is that it might encourage 
someone to help out (with approving new messages), if they otherwise didn't want 
to feel obligated to get involved in a behavior issue.

        New version: 
https://gitlab.com/inkscape/vectors/content/blob/master/articles/Forum%20Rules%20and%20Guidelines/ForumRulesText.md

Thanks again for any comments, suggestions!

brynn