docs: document glMultiDrawElements() fix

(cherry picked from commit ab6bcef99a53217db752659ace105ddfd9b25ebb)
diff --git a/docs/relnotes-7.7.1.html b/docs/relnotes-7.7.1.html
index 959efd9..c3d42c1 100644
--- a/docs/relnotes-7.7.1.html
+++ b/docs/relnotes-7.7.1.html
@@ -44,6 +44,7 @@
 <li>Fixed mipmap generation bug caused by invalid viewport state.
 <li>Gallium SSE codegen for XPD didn't always work.
 <li>Fixed Windows build.
+<li>Fixed broken glMultiDrawElements().
 </ul>