Add release notes for 11.

(cherry picked from commit 12f0388f9cb32016ac0dacaeca631b088b29bb96)
Signed-off-by: Diego Biurrun <diego@biurrun.de>
Mark 11 release in the changelog

Also fix some typos in the entries for the 11 release.

(cherry picked from commit d9792b773516a560ecb99694b8ee745a50027fac)
Signed-off-by: Diego Biurrun <diego@biurrun.de>