abf/abf-ideas#83: added docs for Repository #add_repo_lock_file and #remove_repo_lock_file API actions
abf/abf-ideas#83: updated API docs
abf/abf-ideas#83: added extra info for new actions
Merge pull request #31 from abf/abf-doc:83-lock-files-for-synchronisation-and-publishing
 abf/abf-ideas#83: lock files for synchronisation and publishing.