Improve examples and documentation

examples/lumen.yml

@@ -26,6 +26,8 @@ jobs:
         uses: actions/cache@v1
         with:
           path: ${{ steps.composer-cache.outputs.dir }}
+          # Use composer.json for key, if composer.lock is not committed.
+          # key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }}
           key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
           restore-keys: ${{ runner.os }}-composer-
       - name: Install Composer dependencies