docs: Used groups link attribute to force position of quick-add

Set quick-add to be the first help link under the managing events
section.
docs: Changed page title. Updated to include just adding details

Editing an event is used for both new and existing events. These
changes reflect how the editing window is used for more than one
purpose.
docs: Updates for the different ways you can open the quick-add

Updated docs to include the different ways you can open the
quick-add feature. If you open the quick-add feature with the plus
or ctrl-n, you also need to include the date/time in your details.
If you double-click the desired date/time, you don't need to
include the date/time when typing the event details.
docs: Revised to fix validation errors