docs: fix examples

Author: WillieRuemmele

messages/open.agent.md

@@ -4,7 +4,7 @@ Open an agent in your org's Agent Builder UI in a browser.
 
 # description
 
-Use the api-name flag to open an agent using its API name in the Agent Builder UI of your org. To find the agent's API
+Use the --api-name flag to open an agent using its API name in the Agent Builder UI of your org. To find the agent's API
 name, go to Setup in your org and navigate to the agent's details page.
 
 To generate the URL but not launch it in your browser, specify --url-only.