Merge pull request #1442 from cert-manager/autocompletion

kubectl plugin: explain how to get autocompletion

Author: jetstack-bot

content/docs/reference/cmctl.md

@@ -352,12 +352,26 @@ Resources](https://cert-manager.io/docs/releases/upgrading/remove-deprecated-api
 $ cmctl upgrade migrate-api-version --qps 5 --burst 10
 ```
 
-## Legacy kubectl plugin
+## Kubectl plugin
 
-While the kubectl plugin is supported, it is recommended to use `cmctl` as this enables a better experience via tab auto-completion.
+Since kubectl 1.26, kubectl plugins support auto-completion, which means you will have the same
+experience with the standalone `cmctl` binary and with the kubectl plugin.
 
 To install the plugin you need the `kubectl_cert-manager` file for the platform you're using,
 these can be found on our [cmctl GitHub releases page](https://github.com/cert-manager/cmctl/releases).
 In order to use the kubectl plugin you need its binary to be accessible under the name `kubectl-cert_manager` in your `$PATH`.
 
 You can run `kubectl cert-manager help` to test that the plugin is set up properly.
+
+### Auto-completion with the kubectl plugin
+
+Since kubectl 1.26, it is possible to enable auto-completion for plugins. Assuming that you installed
+`kubectl_cert-manager` in `/usr/local/bin`, you can set up auto-completion by running the following command:
+
+```bash
+cat >kubectl_complete-cert_manager <<'EOF'
+#!/usr/bin/env sh
+kubectl cert-manager __complete "$@"
+EOF
+sudo install kubectl_complete-cert_manager /usr/local/bin
+```