Try not to fail on grep returning no items

Author: rjeberhard

.github/workflows/publish-github-pages.yml

@@ -40,7 +40,7 @@ jobs:
         id: change-check
         run: |
           cd $GITHUB_WORKSPACE/main
-          X=`git diff HEAD~1 --name-only | grep "^documentation" | wc -l`
+          X=`git diff HEAD~1 --name-only | { grep "^documentation" || test $? = 1; } | wc -l`
           if [ $X == "0" ]; then
             echo 'No changes to the documenation'
           else