kiji-rest: REST-152. Fix minor errors in documentation for load testing

issue: https://jira.kiji.org/browse/REST-152
review: https://review.kiji.org/r/2124
commit: https://github.com/kijiproject/kiji-rest/commit/b4b094c1bf6783b4d5f54478e5e30d7ec2b08eb6