MAINTAINERS: Add Mark Russell.

Signed-off-by: Joseph Marrero Corchado <jmarrero@redhat.com>

Author: jmarrero

MAINTAINERS.md

@@ -20,3 +20,4 @@ This group can represent the project for administrative and program manager duti
 | Laura Santamaria  | [nimbinatus](https://github.com/nimbinatus)                          | Red Hat         | Representative   |
 | Mohan Shash       | [mohan-shash](https://github.com/mohan-shash)                        | Red Hat         | Representative   |
 | Preethi Thomas    | [preethit](https://github.com/preethit)                              | Red Hat         | Representative   |
+| Mark Russell      | [marrusl](https://github.com/marrusl)                                | Red Hat         | Representative   |