chore: add dependabot for github actions

.github/dependabot.yml

@@ -0,0 +1,14 @@
+# https://help.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+updates:
+  - package-ecosystem: 'github-actions'
+    directory: '/'
+    schedule:
+      interval: 'weekly'
+      day: 'saturday'
+    labels: [ 'dependencies' ]
+    commit-message:
+      prefix: 'chore'   ## prefix maximum string length of 15
+      include: 'scope'
+    open-pull-requests-limit: 999

.github/workflows/cibuild.yml

@@ -11,8 +11,11 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - name: Checkout
+      # see https://github.com/actions/checkout
+      uses: actions/checkout@v2
     - name: Set up JDK 1.8
+      # see https://github.com/actions/setup-java
       uses: actions/setup-java@v1
       with:
         java-version: 1.8
@@ -36,11 +39,13 @@ jobs:
         cd docgen/xml
         ./gen.sh
     - name: Archive JSON Schema documentation
+      # https://github.com/actions/upload-artifact
       uses: actions/upload-artifact@v2
       with:
         name: JSON-Schema-documentation
         path: docgen/json/docs
     - name: Archive XML Schema documentation
+      # https://github.com/actions/upload-artifact
       uses: actions/upload-artifact@v2
       with:
         name: XML-Schema-documentation