Changed the organisation navigation menu slightly to better handle single organisation mode

locale/en_US/messages.php

@@ -54,7 +54,10 @@ return [
         'MEMBER_COUNT'                   => '# Members <sub>(excl admins)</sub>',
         'ADMIN_COUNT'                    => '# Admins',
 
-        'SELF'                           => 'My Organisations',
+        'SELF'                           => [
+            1 => 'My Organisation',
+            2 => 'My Organisations',
+        ],
         'MANAGE'                         => 'Manage Organisations',
         'ASSIGN_NEW'                     => 'Assign to organisation',