docs: improve helper test for `For`

docs/sources/alerting/rules.md

@@ -52,7 +52,7 @@ Here you can specify the name of the alert rule and how often the scheduler shou
 
 > This setting is available in Grafana 5.4 and above.
 
-The `For` setting allows you to specify a duration for which the alert has to violate the threshold before switching to `Alerting` state and sending notifications. This is useful when you want to reduce the amount of false positive alerts and problems from which the system selfheal. Which in case a human does not need to be woken up.
+If an alert rule has a configured `For` and the query violates the configured threshold it will first go from `OK` to `Pending`. Going from `OK` to `Pending` Grafana will not send any notifications. Once the alert rule has been firing for more than `For` duration, it will change to `Alerting` and send alert notifications. 
 
 Typically, it's always a good idea to use this setting since its often worse to get false positive than wait a few minutes before the alert notification triggers.
 

public/app/features/alerting/partials/alert_tab.html

@@ -39,8 +39,8 @@
             <label class="gf-form-label width-5">For</label>
             <input type="text" class="gf-form-input max-width-6" ng-model="ctrl.alert.for" spellcheck='false' placeholder="5m">
             <info-popover mode="right-absolute">
-              Configuring this value means that an alert rule have to be firing for atleast this duration before changing state.
-              This should reduce false positive alerts and avoid flapping alerts.
+                If an alert rule has a configured For and the query violates the configured threshold it will first go from OK to Pending. 
+                Going from OK to Pending Grafana will not send any notifications. Once the alert rule has been firing for more than For duration, it will change to Alerting and send alert notifications. 
             </info-popover>
           </div>
         </div>