Adjusted the git config user.name/user.email example for what 99% of users would...

Adjusted the git config user.name/user.email example for what 99% of users would like to do

Almost nobody wants to set user.name/user.email on a per-repository
basis as the previous example suggested. I put in a new example that
shows how to use C<git config --global> along with an example of how
to set user.email just for F<perl-git>

I replaced Leon Brocard's name with mine because he didn't fit into
the multiple E-Mail address example and I couldn't think of another
example.