Fix GH Actions workflow docs trigger

This needs to point to the correct title.

Signed-off-by: Peter Goetz <pego@amazon.com>

.github/workflows/docs.yml

@@ -4,7 +4,7 @@ on:
     branches:
       - main
   workflow_run:
-    workflows: [ "Build Docker image used for docs generation" ]
+    workflows: [ "Build Docker image (docs)" ]
     types:
       - completed