fixed code typos in README and formatted a bit

The README had a couple typos: spelled manage.py wrong and also the order of the lines in example of adding a vendor+item was wrong so it wouldn't work (can't add the item until the vendor is saved and its vendor_id is created). Also reformatted things into a couple sections. This is also just to get the hang of using github with the project.  PS - sorry for the 3 commits.. two of them don't actually have any code changes. Also, sorry for changing the file in a way that makes a diff obnoxious.