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/howtos/code/drawing-circles/readme.mdx

@@ -0,0 +1,72 @@
+---
+title: Drawing circles
+---
+
+Real circles are rarely used in pattern design, and they are not part of the
+SVG path specification, but rather a different SVG element.
+
+Still, if you want a circle, you can draw one by calling
+[`Point.addCircle()`](/reference/api/point/addcircle):
+
+<Example caption="An example of adding a path" tutorial>
+```design/src/part.mjs
+function draftPart = ({
+  Point,
+  points,
+  Path,
+  paths,
+  part
+}) {
+
+  points.anchor = new Point(0,0)
+  // highlight-start
+    .addCircle(5, 'lining dotted')
+    .addCircle(10, 'note dashed ')
+    .addCircle(15, 'facing lashed')
+    .addCircle(20, 'interfacing')
+  // highlight-end
+
+  // Prevent clipping
+  paths.demo = new Path()
+    .move(new Point(-20,-20))
+    .move(new Point(20,20))
+
+  return part
+}
+```
+</Example>
+
+:::warning
+Circles are not taken into account when calculating the part's boundary.
+:::
+
+:::note COMMENT (by joost)
+
+##### How multiple circles are implemented
+
+When you add the same attribute multiple times, they are typically joined together
+when rendering. For example multiple calls to add a `class` attribute will end up being
+rendered as `class="class1 class2 class3` which makes a lot of sense.
+
+But when we're placing multiple circles on the same point, that raises a bit of a problem.
+For example in this code:
+
+```js
+point.a = new Point(0,0)
+  .addCircle(10, 'lining')
+  .addCircle(20, 'fabric')
+```
+
+Based on the rules of attributes, this would render a single circle with `r="10 20"
+class="lining fabric"`. Which does not make a lot of sense and is invalid SVG
+as `r` only takes one value.
+
+So the render engine will do some extra work here to check that there are multiple
+circles added, and will render a circle element for each, with the `r` and `class`
+values of their respective calls.
+
+While this is probably what you'd intuitively expect, it is somewhat inconsistent with how
+other attributes are rendered, so I felt it was best to point it out explicitly.
+
+:::
+