feat: Flat import of markdown repo

This is a flat (without history) import of (some of) the content
from our markdown module.

We've imported this without history because the repo contains our
blog posts and showcases posts content prior to porting them to strapi.

Since this contains many images, it would balloon the size of this repo
to import the full history.

Instead, please refer to the history of the (archived) markdown repo
at: https://github.com/freesewing/markdown

markdown/dev/editors/howtos/frontmatter/structure/en.md

@@ -0,0 +1,12 @@
+---
+title: Structure
+order: 20
+---
+
+Frontmatter is made up of `key: value` pairs.
+The value must be quoted if you use a `:` in it to avoid problems parsing the key values:
+
+```md
+title: This does not need to be quoted
+slogan: "Markdown: This is the way"
+```