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/reference/api/utils/units/en.md

@@ -0,0 +1,20 @@
+---
+title: units()
+---
+
+```js
+string utils.units(float value, string format = 'metric')
+```
+
+Converts the units `value` you pass it into a formatted string for the `format` you pass it.
+
+Format must be either `imperial` or `metric` (the default).
+
+<Tip>
+
+The [Part.shorthand](/reference/api/part/shorthand/) call provides a context-aware
+`unit()` method that will call this method and pass it the units requested by the user.
+
+</Tip>
+
+