Two rules have been specified for yamlfmt here:
* Automatically add the header `---` to YAML files.
* Preserve line breaks.
ref:
https://github.com/google/yamlfmt/blob/main/docs/config-file.md#configuration-1
Signed-off-by: Jintao Zhang <zhangjintao9020@gmail.com>
Co-authored-by: Marek Siarkowicz <siarkowicz@google.com>
