[REVISED] Update to 12.0-RELEASE schedule

The 12.0-RELEASE schedule will slip while last-minute work-in-progress
continues to be completed before branching stable/12.

At present, the project branch used to update OpenSSL to version 1.1.1
is expected to be ready to merge to head at some point early next week.
As such, to err on the side of caution, the branch point of stable/12 is
now planned for October 12 in order to plan for at least one ALPHA build
before beginning the BETA build phase of the release cycle.

The 12.0 schedule has been updated on the website at:

    https://www.freebsd.org/releases/12.0R/schedule.html

Thank you in advance for your patience.

Glen
On behalf of:	re_at_