docs: add release notes for 19.1.8

Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com>

docs/relnotes/19.1.8.html

diff --git a/docs/relnotes/19.1.8.html b/docs/relnotes/19.1.8.html
index 9f4862c..f1851fe 100644
--- a/docs/relnotes/19.1.8.html
+++ b/docs/relnotes/19.1.8.html
@@ -35,7 +35,7 @@
 
 <h2>SHA256 checksums</h2>
 <pre>
-TBD
+f0fe8289b7d147943bf2fc2147833254881577e8f9ed3d94ddb39e430e711725  mesa-19.1.8.tar.xz
 </pre>