Update help.php

Have removed bootstrap classes from the header warpper and let 
it go to max width to match up with the events.php change.
This isn't quite as neat, but it is pretty much bootstrap 
version agnostic.

Also changed the size and flow of the well wit contents so it 
doesn't fall out of the container in 5.6.x.

Both not as good as the original in 5.5, but minimal changes 
to make it look ok in 5.6.x