Update querying-relationships.md (#678)

#Roles & Permissions Absence
I think there is a mistake on the query of User::whereDoesntHavePermission()->get(), i believe it should be User::whereDoesntHavePermission()->get()

docs/docs/8.x/usage/querying-relationships.md

@@ -87,5 +87,5 @@ To retrive all the users that don't have any roles or permissions you can use:
 ```php
 User::whereDoesntHaveRoles()->get();
 
-User::whereDoesntHavePermission()->get();
+User::whereDoesntHavePermissions()->get();
 ```