chore: Port FreeSewing.dev to docusaurus

The replaces the NextJS site powering FreeSewing.dev with a Docusaurus
setup. It's part of my efforts to simplify FreeSewing's setup so we can
focus on our core value proposition.

sites/dev/docs/reference/api/point/sitson/readme.mdx

@@ -0,0 +1,47 @@
+---
+title: Point.sitsOn()
+---
+
+The `Point.sitsOn()` method returns `true` if this point has the _exact_ same
+coordinates as the point you pass to it.
+
+## Signature
+
+```js
+bool point.sitsOn(Point check)
+```
+
+## Example
+
+<Example caption="An example of the Point.sitsOn() method">
+```js
+({ Point, points, Path, paths, Snippet, snippets, part }) => {
+
+  let s
+  for (let i = 0; i < 10; i++) {
+    points[`a${i}`] = new Point(i * 10, 40)
+    points[`b${i}`] = new Point(i * 10, i * 8)
+    if (points[`a${i}`].sitsOn(points[`b${i}`])) s = "notch"
+    else s = "bnotch"
+    snippets[`b${i}`] = new Snippet(s, points[`b${i}`])
+    snippets[`a${i}`] = new Snippet(s, points[`a${i}`])
+  }
+
+  // Prevent clipping
+  paths.diag = new Path()
+    .move(new Point(0,0))
+    .move(new Point(90,70))
+
+  return part
+}
+```
+</Example>
+
+## Notes
+
+This method uses strict comparison. So points with an X-coordinate of `10` and
+`10.0001` are considered to be different.
+
+To check if two points have the same coordinates rounded to the nearest
+millimeter, use [`Point.sitsRoughlyOn()`](/reference/api/point/sitsroughlyon/)
+instead.