Edit multiuser.md

-Remove typos
-Add a link to bootstrap.css in the login screen html where bootstrap classes are referenced
-Add a note that jquery is loaded automatically for every VWF app
-Edit "What needs to be created" section to show a clearer grouping that is now reflected in the later sections
-Remove one reference to "his" to be more gender neutral.  However, I introduced another when I removed a disagreement in number (using "theirs" to refer to a single person)