Promote chrischdi to Cluster API maintainer

Author: chrischdi

OWNERS_ALIASES

@@ -19,6 +19,7 @@ aliases:
 
   # non-admin folks who have write-access and can approve any PRs in the repo
   cluster-api-maintainers:
+  - chrischdi
   - enxebre
   - fabriziopandini
   - killianmuldoon
@@ -27,7 +28,6 @@ aliases:
 
   # folks who can review and LGTM any PRs in the repo
   cluster-api-reviewers:
-  - chrischdi
   - jackfrancis
   - JoelSpeed
   - richardcase