docs: Updated add-calendar page to reflect UI change

Per commit 2bf33bf42125d1bbf7400eaccf4f092ae0bd5bd4, the UI will
include Web calendar (.ics or webcal). This update reflects
this change.
docs: Removed add-recurring event page. Refactored view page.

We cover how to add a recurring event in the main add-an-event
page. Also, I refactored the page about viewing the calendar to
reflect how the "today" option can be used to return your
calendar view to the current day.
docs: Added page about removing events

Describe how to remove both single and recurring events.
docs: Removed link to remove-page stub

I'll be describing how to remove calendars in the future, once
that functionality is fleshed out a bit more.