Add kubectl plugin

cmd/plugin/ingress-nginx.yaml.tmpl

@@ -0,0 +1,40 @@
+apiVersion: krew.googlecontainertools.github.com/v1alpha2
+kind: Plugin
+metadata:
+  name: ingress-nginx
+spec:
+  shortDescription: Interact with ingress-nginx
+  description: |
+    The official kubectl plugin for ingress-nginx.
+  version: %%%tag%%%
+  platforms:
+  - uri: https://github.com/kubernetes/ingress-nginx/releases/download/nginx-%%%tag%%%/kubectl-ingress_nginx-darwin-amd64.tar.gz
+    sha256: %%%shasum_darwin_amd64%%%
+    files:
+    - from: "*"
+      to: "."
+    bin: "./kubectl-ingress_nginx"
+    selector:
+      matchLabels:
+        os: darwin
+        arch: amd64
+  - uri: https://github.com/kubernetes/ingress-nginx/releases/download/nginx-%%%tag%%%/kubectl-ingress_nginx-linux-amd64.tar.gz
+    sha256: %%%shasum_linux_amd64%%%
+    files:
+    - from: "*"
+      to: "."
+    bin: "./kubectl-ingress_nginx"
+    selector:
+      matchLabels:
+        os: linux
+        arch: amd64
+  - uri: https://github.com/kubernetes/ingress-nginx/releases/download/nginx-%%%tag%%%/kubectl-ingress_nginx-windows-amd64.tar.gz
+    sha256: %%%shasum_windows_amd64%%%
+    files:
+    - from: "*"
+      to: "."
+    bin: "./kubectl-ingress_nginx"
+    selector:
+      matchLabels:
+        os: windows
+        arch: amd64