project: ci_service should only catch ci services

ci_service should return true if a ci service is enabled.  Currently
it's checking for any service being enabled instead of only services in
the ci category.
Small spelling correction in the readme.
Merge pull request #7068 from chino/only-check-ci-status-when-ci-service-enabled

project: ci_service should only catch ci services
Merge branch 'master' of github.com:gitlabhq/gitlabhq
Add some entries to changelog

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Update docs to markdown style guide.