Squashed 'libertree-backend-rb/' changes from ece3061..4bc5944

4bc5944 it's better not to overwrite config.yaml

git-subtree-dir: libertree-backend-rb
git-subtree-split: 4bc594491c09a2228ccc06ce645aab53c5a55a2c
Merge commit '58f1c3849f49f27391270ec346d7487dbd366f32'
bump version numbers, add config.yaml.example to backend
add more info about required configuration