When you import content to your Prismic repository using the Import/Export feature, your content needs to be in a compatible JSON format.
There are a couple of community-made tools that can help convert either Markdown or raw HTML into the proper JSON format to add the content to a Rich Text field. These are:
- kramdown-prismic: A Ruby tool to convert Markdown or HTML documents to Prismic's Rich Text JSON format
- prismic-importer: A PHP tool to convert Markdown into Prismic-compatible JSON.
- wordprismic: A Node.js tool for converting WordPress content into Prismic-compatible JSON.