docs: add sha256 checksums for 11.1.4

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

docs/relnotes/11.1.4.html

@@ -31,7 +31,8 @@ because compatibility contexts are not supported.
 
 <h2>SHA256 checksums</h2>
 <pre>
-TBD
+034231fffb22621dadb8e4a968cb44752b8b68db7a2417568d63c275b3490cea  mesa-11.1.4.tar.gz
+0f781e9072655305f576efd4204d183bf99ac8cb8d9e0dd9fc2b4093230a0eba  mesa-11.1.4.tar.xz
 </pre>