Announce: delaying 2.11 final by one week

We'd like to cook and merge a few hot-fix topics to 'master' before
the upcoming release, in order to fix minor regressions in
"stripspace" (which affects "rebase -i"), "archive" and "mailinfo"
that were introduced during this cycle.  So I'll be cutting -rc3
soon this week, and hopefully tagging the final by the end of this
month.

Thanks.