Documentation: CSS Updates other formatting, grammatical changes

I made some CSS updates, specifically for version tags and <pre> blocks to make things pop a bit. I also removed the MySQL Cluster reference to the providers list (I'm guessing we're not going to be getting to that anytime soon). Also indented some of the version tags when there referenced commands, at least in a few of the help pages.

Still to do is to make the option reference consistent. Sometimes .. describe:: is used while other times "**command** = type" is used. For HTML, I prefer the latter since it's easier and more explicit but I suspect the former would be much more compatible for non-HTML formats.