Sorry for the double-duty pull request but my other changes were minor enough that I figured it would be silly to have a second pull request just for them.
I created the general best practices page for information that should be used for the whole site unless otherwise overridden (e.g. navigation may be different for a gemlog). So far there's file naming recommendations that pull from gemlog.md & standard practice on the web and information (basically pulled from the spec) on alt text for preformatted text strings.
I think these were excellent additions. I'm going to merge!