Skip build on documentation commits

.github/workflows/build.yaml

@@ -16,6 +16,11 @@ jobs:
 
     steps:
     - uses: actions/checkout@v1
+    - name: Should this run?
+      run: |
+        COUNT=$(git diff --name-only HEAD~1 | wc -l)
+        if [ $COUNT = 1 ]; then git diff --name-only HEAD~1 | grep README; fi
+        if [ $? = 0 ]; then echo 'Only the README has changed, skipping build.'; exit 66; fi
     - name: Use Node.js ${{ matrix.node-version }}
       uses: actions/setup-node@v1
       with: