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/howtos/code/storing-path-length/en.md

@@ -0,0 +1,30 @@
+---
+title: Storing the seam length to use in another part
+for: developers
+about: Shows how to store a seam length so you can true the seam of another part
+---
+
+<Note>
+
+##### See this example in our source code
+
+ - [packages/aaron/src/front.js](https://github.com/freesewing/freesewing/blob/develop/packages/aaron/src/front.js#L103)
+
+</Note>
+
+Often when designing patterns, we need to _true a seam_ which means to make sure
+that two parts that need to be joined together are the same distance.
+
+The example below is from Aaron and stores the length of the armhole seam:
+
+```js
+  // Store length of armhole and neck opening
+  store.set(
+    'frontArmholeLength',
+    new Path()
+      .move(points.armhole)
+      .curve(points.armholeCp2, points.strapRightCp1, points.strapRight)
+      .length()
+  )
+```
+