Add support for MDX

[zenorocha]

Inspiration:

• https://www.joshwcomeau.com/react/wonderful-emails-with-mjml-and-mdx/#composing-emails-with-mdx
• https://www.useplunk.com/markdown-to-email

Components needed:

• Create Ol component #53
• Create Ul component #52
• Create Pre component #49
• Create Code component #48
• Create P component #42
• Create Heading component #13

[vcapretz]

Assigned myself for this one, going to work on it!

[Dan86de]

Any update on support for mdx?

[bukinoshita]

Hey guys, we just merged this PR #707

[dngpng]

when will this be released?

[bukinoshita]

Just released https://www.npmjs.com/package/@react-email/markdown

[Dan86de]

Gr8 will check this one :)