commonmark is used in the swift compiler
gerald.bauer at gmail.com
Sun Dec 6 03:40:02 EST 2015
Good catch. Thanks for sharing. As always Apple copies Microsoft ;-)
Microsoft's "new" open source Visual Studio Code  has built-in
support for Markdown (e.g. highlighting, live preview, etc.)  and
is itself documented in Markdown  including the website.
PS: Apple is using ReStructuredText (RsT) for it's Swift docs.
More information about the Markdown-Discuss