docs: add inspector hint for example

Author: chr-hertel

examples/cli/README.md

@@ -21,3 +21,9 @@ DEBUG=1 php index.php
 You will see debug outputs to help you understand what is happening.
 
 In this terminal you can now test add some json strings. See `example-requests.json`.
+
+Run with Inspector:
+
+```bash
+npx @modelcontextprotocol/inspector php index.php
+```