docs: update the sha256 checksums for 11.2.1

Turns out the previous tarballs got corrupted during upload which I
carelessly forgot to check prior to deleting the local ones.
Lesson learned - double check before removing the local ones.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
(cherry picked from commit 79b0e13913b5189bb8629e80439fea746f99fe79)
1 file changed