[Feature Request]: Add support for YAML

[rytswd]

🔮 Relevant Command

importer purge, importer update, importer generate, importer preview

🗂 Language Type

YAML

🔎 Request Details

YAML support on top of Markdown.

There may be a need of handling indentation for this. The default behaviour should be to keep the original file content as is, and possibly add some option for adding/removing indentation.