fix reference to sheriff-o-matic readme
fix reference to sheriff-o-matic readme

R=ojan@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/488643004

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@180584 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs