Add link to Git Configure page

It's kind of important for project maintainers, and especially Core maintainers, to configure Git properly. There's a good docs page about this: https://drupal.org/documentation/git/configure

But it's hard to find. Here's my story from yesterday and today:

timplunkett had alerted me to some of those config commands a while back, and I just got a new laptop and knew I needed to do some configuration to avoid rebase commits littering the Core commit log at least. So I first went to the version control tab on a project I maintain hoping it would tell me how to do the auto-rebase thing, but it didn't. Then I followed any links from there to see if it would tell me what to do, but none of them did either. So I ended up pinging timplunkett in IRC today and he pointed me to the Configure page (which used to be buried under Installing Git, but I daylighted it up one level and also added some links from the module maintainers page to there so hopefully people can find this page a little easier)...

Anyway, I think it's kind of important at least for maintainers to configure Git properly, so I think we should have a link to the Configure page on the Version Control tab.

Probably it should go in the "One Time Only" section. Maybe at the end of the "Associating your copy of the repository with your Drupal.org account" sub-section? It could just say:

It is also important to (link)configure git properly(/link).

where (link) would go to https://drupal.org/documentation/git/configure