Fix typo in yml docs

From c09734822e2a6c79a345b6755c79b870f34007e0

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Add link to docker-osx in yml docs

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Merge pull request #347 from orchardup/fix-typo-yml-docs

Fix typo yml docs