Update README.rst

Updated all instances of the institution name from either mkdriveninst or mktdriveninst to MktDrivenInst
Hi @mwnelson ! This is the only change I'll request: instead of changing this line, just delete it.  This line isn't doing anything since I'm not wrapping the docs with sphinx.

(I make this change to your pull request, but changes are typically suggested by the reviewer, but made by the submitter. If you're in this for experience, we may as well do it the right way!)
You probably know this, but the way this works is : 
- you make a pull request (done!)
- I look at it and make comments on things that are awesome, questionable, or need to be changed (done!)
- You make changes accordingly to your patch-1 branch and push those commits to mwnelson/patch-1 (that will automagically update the pull request here)
- I pull patch-1 once it satisfies all my desires