CFC: make side effect of Follow activity consistent (Issue #320)

This is a call for consensus to apply an erratum to the ActivityPub 
specification. If there are no objections in the next 14 calendar days, 
I will add this text to the errata for ActivityPub and apply the 
corresponding change to the editor's draft.

More discussion of the issue is available at: 
https://github.com/w3c/activitypub/issues/320

The erratum is as follows:

In section 7.5 "Follow Activity", the second paragraph erroneously 
describes processing requirements for receiving an Accept activity with 
a Follow activity as the object. It describes changing the "followers" 
collection; however, receiving an "Accept" activity over the federation 
protocol would result in a change to the "following" collection. The 
correct behaviour is already described in section 7.6 "Accept Activity". 
One possible correction is to simply remove the second paragraph of 
section 7.5.


Evan