Adjustments to the 10.1-RELEASE schedule:

 - Add 10.1-RC4 as a late addition.
 - Adjust the dates for 10.1-RELEASE builds and
   announcement.

Approved by:	re (implicit)
Sponsored by:	The FreeBSD Foundation


git-svn-id: svn+ssh://svn.freebsd.org/doc/head@45869 c2e8774f-c49f-e111-b436-862b2bbc8956