The body of a comment can be written in GitHub Flavored Markdown. issues, issue comments, pull request comments, and the gist comments APIs all accept these same media types:
application/vnd.github.VERSION.raw+json
Return the raw markdown body. Response will include body. This is the
default if you do not pass any specific media type.
application/vnd.github.VERSION.text+json
Return a text only representation of the markdown body. Response will
include body_text.
application/vnd.github.VERSION.html+json
Return HTML rendered from the body's markdown. Response will include
body_html.
application/vnd.github.VERSION.full+json
Return raw, text and HTML representations. Response will include body,
body_text, and body_html: