adds gh action for release

Author: marshallford

.github/workflows/release.yaml

@@ -0,0 +1,37 @@
+on:
+  push:
+    tags:
+    - 'v*'
+name: release
+jobs:
+  release:
+    name: release
+    runs-on: ubuntu-20.04
+    steps:
+    - name: checkout
+      uses: actions/checkout@v2
+    - name: get version
+      id: get_version
+      run: |
+        echo ::set-output name=TAG::${GITHUB_REF/refs\/tags\//}
+        echo ::set-output name=VERSION::${GITHUB_REF/refs\/tags\/v/}
+    - name: create release
+      uses: actions/create-release@v1
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      with:
+        tag_name: ${{ github.ref }}
+        release_name: ${{ steps.get_version.outputs.TAG }}
+        prerelease: ${{ endsWith(steps.get_version.outputs.TAG, '-dev') }}
+        body: |
+          See [README](https://github.com/marshallford/default-allow-privilege-escalation/blob/${{ steps.get_version.outputs.TAG }}/README.md) for install instructions.
+
+          **container image:**
+          ```
+          docker pull docker.io/marshallford/default-allow-privilege-escalation:${{ steps.get_version.outputs.VERSION }}
+          ```
+
+          **kustomize:**
+          ```
+          kustomize build github.com/marshallford/default-allow-privilege-escalation/deploy?ref=${{ steps.get_version.outputs.TAG }}
+          ```