Add new signal logentry_object_link

doc/development/api/general.rst

@@ -51,7 +51,7 @@ Backend
 
 
 .. automodule:: pretix.base.signals
-   :members: logentry_display, requiredaction_display
+   :members: logentry_display, logentry_object_link, requiredaction_display
 
 Vouchers
 """"""""

doc/development/api/plugins.rst

@@ -114,6 +114,19 @@ method to make your receivers available::
         def ready(self):
             from . import signals  # NOQA
 
+You can optionally specify code that is executed when your plugin is activated for an event
+in the ``installed`` method::
+
+    class PaypalApp(AppConfig):
+        …
+
+        def installed(self, event):
+            pass  # Your code here
+
+
+Note that ``installed`` will *not* be called if the plugin in indirectly activated for an event
+because the event is created with settings copied from another event.
+
 Views
 -----