[DOCS] Document e:uri.page ViewHelper

Refs #1212

Documentation/ForAdministrators/CustomNotifications/Index.rst

@@ -119,3 +119,10 @@ paid and confirmed to the event.
 
 Also note, that the usage of conditions like shown above are rudimentary and does not cover all
 scenarios.
+
+How to create links to actions for notifications sent using the backend module
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The native :php:`f:uri.action` ViewHelper will create links in backend context when used for notifications in the
+backend module. In order to create links in frontend context, the extension comes with an a custom ViewHelper,
+which creates links for frontend context. See :php:`Uri.PageViewhelper` in :ref:`viewhelpers`

Documentation/ForAdministrators/Templates/Viewhelpers/Index.rst

@@ -77,10 +77,18 @@ generated in the TYPO3 backend.
 This viewhelper can be used in email templates for custom notifications, when you want to link to a
 given page in you TYPO3 website.
 
-**Example**::
+**Example 1**::
 
   <e:uri.page pageUid="4" additionalParams="{tx_sfeventmgt_pieventdetail:{event: registration.event, action: 'detail', controller: 'Event'}}" absolute="1"/>
 
+**Example 2**::
+
+  <a href="{e:uri.page(
+      pageUid: 123,
+      additionalParams: '{tx_sfeventmgt_pieventregistration: {pluginName:\'Pieventregistration\',extensionName:\'sfeventmgt\',action:\'cancelRegistration\',controller:\'Event\',reguid: registration.uid, hmac: hmac}}',
+      absolute: 1,
+  )}" class="button">Remove registration</a>
+
 Uri.OnlineCalendar
 ~~~~~~~~~~~~~~~~~~