Initial implementation of test workflow.

.github/workflows/test.yml

@@ -0,0 +1,17 @@
+name: Test
+
+on:
+  pull_request:
+  push:
+  workflow_dispatch:
+
+jobs:
+  test:
+    name: Test markdownlint-cli2-action
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+    steps:
+    - uses: actions/checkout@v2
+    - name: No inputs
+      uses: ./