Consolidate announcement and plan fields and update instructions

[ohemorange]

from #843 (comment)

what if we changed all/most current plan links to announcements and made the following changes to the instructions:

• say full should have an announcement and "shouldn't need a tutorial to turn on https. an exception might include instructions of what to do if something goes wrong and the automatic https doesn't work."
• say plan is no longer used and should be left as ""

this allows us to consolidate the two fields in a way that definitely doesn't require anything from e&d