Add depenednecy.

Author: zzap

docs/overview.md

@@ -4,6 +4,8 @@
 
 ### Dependencies
 
+WP-CLI `ai` command utilizes [AI Services](https://github.com/felixarntz/ai-services/) plugin by [Felix Arntz](https://github.com/felixarntz).
+
 ## Problem
 
 ## Key features