Group Nesting Mode All UX improvements

Update the description (and possibly the title) of the Group "Nesting Mode All" field.

Change the current description which reads "For membership in this Group via Nested Groups, require membership in _all Nested (Source) Groups to be a member of this Group (instead of any)"

to something like

"When enabled, a Person must be found in all nested groups to be included as a member. When disabled, a Person found in any nested group will be included. Also note that nested groups marked for "exclusion" take priority over nested groups used for inclusion."

This is based on the description found in the wiki documentation.