Cleanup the OWNERS files (#364)

Author: mkumatag

OWNERS

@@ -1,13 +1,22 @@
 # See the OWNERS docs: https://git.k8s.io/community/contributors/guide/owners.md
 
 approvers:
-  - sig-cluster-lifecycle-leads
-  - cluster-api-admins
-  - cluster-api-maintainers
-  - cluster-api-ibmcloud-maintainers
+- gyliu513
+- jichenjc
+- mkumatag
 
 reviewers:
-  - provider-ibmcloud-leads
-  - cluster-api-maintainers
-  - cluster-api-ibmcloud-maintainers
-  - cluster-api-ibmcloud-reviewers
+- gyliu513
+- jichenjc
+- mkumatag
+
+emeritus_approvers:
+- xunpan
+
+emeritus_reviewers:
+- bradtopol
+- clyang82
+- hchenxa
+- morvencao
+- spzala
+- xunpan