fix 2.7.1 release notes doc typos
fix 2.7.1 release notes doc typos

Signed-off-by: Maria Shaldibina <dc03896a0185453e5852a5e0f0fab6cbd2e026ff@pivotal.io>
Signed-off-by: Josh Zarrabi <9a6580bc8b1126be59192e8efe26eb0c314614aa@pivotal.io>

concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse