chore: Update Marsh Gardiner's affiliation (#393)

Updated Marsh Gardiner's affiliation from empty to Rubrik.

Author: earth2marsh

MAINTAINERS.md

@@ -12,7 +12,7 @@ approval privileges to the aep-dev organization.
 | Dan Hudlow      | [@hudlow](https://github.com/hudlow)             | IBM            |
 | Mike Kistler    | [@mkistler](https://github.com/mkistler)         | Microsoft      |
 | Mak Ahmad       | [@makahmad](https://github.com/makahmad)         |                |
-| Marsh Gardiner  | [@earth2marsh](https://github.com/earth2marsh)   |                |
+| Marsh Gardiner  | [@earth2marsh](https://github.com/earth2marsh)   | Rubrik         |
 | Richard Frankel | [@rofrankel](https://github.com/rofrankel)       | Roblox         |
 | Richard Gibson  | [@gibson042](https://github.com/gibson042)       | Algoric        |
 | Yusuke Tsutsumi | [@toumorokoshi](https://github.com/toumorokoshi) | General Motors |