Add missing localization

public/language/en_GB/groups.json

@@ -43,6 +43,7 @@
 	"details.private_help": "If enabled, joining of groups requires approval from a group owner",
 	"details.hidden": "Hidden",
 	"details.hidden_help": "If enabled, this group will not be found in the groups listing, and users will have to be invited manually",
+	"details.delete_group": "Delete Group",
 
 	"event.updated": "Group details have been updated",
 	"event.deleted": "The group \"%1\" has been deleted",