Docs: Update running manually documentation with information about OTP

Issue: #3078
PR: #3206

Author: shreyamalviya

docs/content/usage/running-manually.md

@@ -13,6 +13,13 @@ tags: ["usage"]
 A command to run the Agent manually can be generated by the Island Server UI by
 going to the "Run Monkey" -> "Manual" page.
 
+Any Agent, when run, needs to authenticate with the Island using a one-time
+password (OTP) whose validity is 2 minutes. The commands on the
+"Run Monkey" -> "Manual" page are updated with a valid OTP each time a command is
+copied or the OTP expires.
+
+![Manual run command](/images/island/run_monkey_page/run_monkey_on_machine.png "Manual run command")
+
 ### Downloading the Agent manually
 
 Agent binaries can be downloaded by sending a `GET` request to