Update user documentation

The documentation mentions a bug in MariaDB 10.2.9 that causes problems
with the new users query.

Documentation/Getting-Started/Configuration-Guide.md

@@ -909,30 +909,12 @@ GRANT SELECT ON mysql.roles_mapping TO 'maxscale'@'maxscalehost';
 GRANT SHOW DATABASES ON *.* TO 'maxscale'@'maxscalehost';
 ```
 
-MariaDB MaxScale will execute the following query to retrieve the users. If you
+See [MaxScale Troubleshooting](https://mariadb.com/kb/en/mariadb-enterprise/maxscale-troubleshooting/)
-suspect that you might have problems with grants, it is recommended to run this
+for more information on how to troubleshoot authentication related problems.
-query and see the results it returns.
 
-```
+**Note:** Due to a bug in MariaDB 10.2.9, if you see a
-SELECT DISTINCT
+          `SELECT command denied to user ... for table 'users'`
-    user.user AS user,
+          error, grant `SELECT ON mysql.*` to this user.
-    user.host AS host,
-    user.password AS password,
-    concat(user.user,user.host,user.password,
-      IF((user.Select_priv+0)||find_in_set('Select',Coalesce(tp.Table_priv,0)),'Y','N') ,
-      COALESCE( db.db,tp.db, '')) AS userdata,
-    user.Select_priv AS anydb,
-    COALESCE( db.db,tp.db, NULL) AS db
-    FROM
-    mysql.user LEFT JOIN
-    mysql.db ON user.user=db.user AND user.host=db.host LEFT JOIN
-    mysql.tables_priv tp ON user.user=tp.user AND user.host=tp.host
-    WHERE user.user IS NOT NULL AND user.user <> ''
-```
-
-In versions of MySQL 5.7.6 and later, the `Password` column was replaced by
-`authentication_string`. Change `user.password` above with
-`user.authentication_string`.
 
 <a id="passwd"></a>
 #### `password`