Update docs

Document new mouse action open_url and rule action_name in dunstrc and docs/dunst.5.pod.

docs/dunst.5.pod

@@ -524,7 +524,13 @@ Don't do anything.
 
 =item B<do_action> (default for mouse_middle_click)
 
-If the notification has exactly one action, or one is marked as default, invoke it. If there are multiple and no default, open the context menu.
+Invoke the action determined by the action_name rule. If there is no such
+action, open the context menu.
+
+=item B<open_url>
+
+If the notification has exactly one url, open it. If there are multiple
+ones, open the context menu.
 
 =item B<close_current> (default for mouse_left_click)
 
@@ -868,6 +874,13 @@ later. Use C<msg_urgency> to match it.
 Setting this to true will prevent the notification from being displayed
 initially but will be saved in history for later viewing.
 
+=item C<action_name>
+
+Sets the name of the action to be invoked on do_action. If not specified, the
+action set as default action or the only available action will be invoked.
+
+Default: "default"
+
 =back
 
 As with the filtering attributes, each one corresponds to

dunstrc

@@ -277,8 +277,10 @@
     # Defines list of actions for each mouse event
     # Possible values are:
     # * none: Don't do anything.
-    # * do_action: If the notification has exactly one action, or one is marked as default,
+    # * do_action: Invoke the action determined by the action_name rule. If there is no
-    #              invoke it. If there are multiple and no default, open the context menu.
+    #              such action, open the context menu.
+    # * open_url: If the notification has exactly one url, open it. If there are multiple
+    #             ones, open the context menu.
     # * close_current: Close current notification.
     # * close_all: Close all notifications.
     # * context: Open context menu for the notification.
@@ -375,6 +377,7 @@
 #    set_transient
 #    timeout
 #    urgency
+#    action_name
 #
 # Shell-like globbing will get expanded.
 #