docs: add sha256 sums for 21.2.6 relnotes
diff --git a/docs/relnotes/21.2.6.rst b/docs/relnotes/21.2.6.rst
index e36e409..38c84a4 100644
--- a/docs/relnotes/21.2.6.rst
+++ b/docs/relnotes/21.2.6.rst
@@ -19,7 +19,7 @@
 
 ::
 
-    TBD.
+   1e7e22d93c6e8859fa044b1121119d26b2e67e4184b92ebb81c66497dc80c954  mesa-21.2.6.tar.xz
 
 
 New features