feat: completion command (#1157)

website/docs/deprecations/completion_scripts.mdx

@@ -0,0 +1,25 @@
+---
+slug: /deprecations/completion-scripts/
+---
+
+# Completion Scripts
+
+:::warning
+
+This deprecation breaks the following functionality:
+
+- Any direct references to the completion scripts in the Task git repository
+
+:::
+
+Direct use of the completion scripts in the `completion/*` directory of the
+[github.com/go-task/task][task] Git repository is deprecated. Any shell
+configuration that directly refers to these scripts will potentially break in
+the future as the scripts may be moved or deleted entirely. Any configuration
+should be updated to use the [new method for generating shell
+completions][completions] instead.
+
+{/* prettier-ignore-start */}
+[completions]: ../installation.mdx#setup-completions
+[task]: https://github.com/go-task/task
+{/* prettier-ignore-end */}