docs: add sha256 checksums for 12.0.5

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
(cherry picked from commit 6b1c3c3aa0a2b643dbb9964b7001097eed3c4888)
diff --git a/docs/relnotes/12.0.5.html b/docs/relnotes/12.0.5.html
index d69a614..08fa068 100644
--- a/docs/relnotes/12.0.5.html
+++ b/docs/relnotes/12.0.5.html
@@ -31,7 +31,8 @@
 
 <h2>SHA256 checksums</h2>
 <pre>
-TBD
+44d08a27d98bfeacd864381189e434d98afbf451689d01f80380dc1d66450e5b  mesa-12.0.5.tar.gz
+2b0a972d8282860a11291c09c3ef01ac45171405951eb21a83c45ed2b4321924  mesa-12.0.5.tar.xz
 </pre>