Specified the requirement to enable the endpoint to use it (#2934)

guide/content/en/plugins/sanic-ext/health-monitor.md

@@ -12,12 +12,13 @@ You can setup Sanic Extensions to monitor the health of your worker processes. T
 
 .. column::
 
-    Out of the box, the health monitor is disabled. You will need to opt-in if you would like to use it.
+    Out of the box, the health monitor is disabled. You will need to opt-in and enable the endpoint if you would like to use it.
 
 .. column::
 
     ```python
     app.config.HEALTH = True
+    app.config.HEALTH_ENDPOINT = True
     ```
 
 ## How does it work