Add krew-release-bot support (#189)

* try github actions

* create release

* open pr using krew-release-bot

.github/workflows/release.yml

@@ -0,0 +1,29 @@
+name: release
+on:
+  push:
+    tags:
+    - 'v*.*.*'
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@master
+    - name: Create Release
+      id: create_release
+      uses: actions/create-release@v1
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      with:
+        tag_name: ${{ github.ref }}
+        release_name: Release ${{ github.ref }}
+    - name: Update new version for plugin 'ctx' in krew-index
+      uses: rajatjindal/krew-release-bot@v0.0.31
+      with:
+        krew_template_file: .krew/ctx.yaml
+    - name: Update new version for plugin 'ns' in krew-index
+      uses: rajatjindal/krew-release-bot@v0.0.31
+      with:
+        krew_template_file: .krew/ns.yaml 
+
+