Automatically generate reference docs for all workloads and traits.
1) moved design part from hack/references/configurations/rollout.yaml to design/vela-core/rollout.md
2) added usages for all workloads/traits, except route (#672)
3) renamed some reference docs
Attention: atuo-generation of specifications for all parameters has NOT been implemented, they are generated
based on files under `hack/references/configurations`
Co-authored-by: Jianbo Sun <wonderflow.sun@gmail.com>