annotations: SCHEMA-754. Update REVIEWERS file in kiji-annotations.

Update kiji-annotations REVIEWERS from aaron to lsheng and milo.

issue: https://jira.kiji.org/browse/SCHEMA-754
review: https://review.kiji.org/r/1805
commit: https://github.com/kijiproject/annotations/commit/197638afca019191072c673cd81ea8c5fa61e14f
bento-cluster: CLUSTER-37. Update REVIEWERS file in bento-cluster.

issue: https://jira.kiji.org/browse/CLUSTER-37
review: https://review.kiji.org/r/1806
commit: https://github.com/kijiproject/bento-cluster/commit/03cd83aa75f5bb349e095f1c886269daf8ac49cc