Updated "Partially correct" section of Moodle Help

This week, I found out about a glitch in the way Moodle was reporting the item score for Partially correct items in online tests and practices.  So I've been tweaking the settings on all the tests to avoid any issues. 

I also updated the section on Partially correct at lionden.com/moodle-test-items.htm#partial to more clearly explain scoring on such items.