Add myself to client-go reviewers

Given the ongoing work on generifying client-go, it might make sense
for me to be a reviewer (at least to keep better track of changes
being made before they go in).

Signed-off-by: Stephen Kitt <skitt@redhat.com>

staging/src/k8s.io/client-go/OWNERS

@@ -16,6 +16,7 @@ reviewers:
   - deads2k
   - jpbetz
   - liggitt
+  - skitt
   - soltysh
   - sttts
   - yliaog