Documentation update for install instructions.

I have added documentation for installation as well as for enabling support for languages indicating the preferred method of each. As requested I have left in the old instructions (and made it clear that there are easier ways) for how to install and configure smart-tabs-mode. If there's anything you need me to change let me know, or if there's anything you want to tweak go right ahead :) Sorry it took so long to reply. Internet at my place has been wonky and I haven't been able to get online (N).