chore(markdown): Move non-api docs to reference

markdown/dev/reference/macros/rmad/en.md

@@ -0,0 +1,41 @@
+---
+title: rmad
+---
+
+The `rmad` macro removes all dimensions with the exception of those that were
+created with a custom ID.  It is provided by the [dimension
+plugin](/reference/plugins/dimension/).
+
+## Signature
+
+```js
+macro('rmad')
+```
+
+## Example
+
+<Example caption="An example of the rmad macro">
+```js
+({ Point, macro, part }) => {
+
+  // This will be removed
+  macro('ld', {
+    from: new Point(10, 0),
+    to: new Point(40, 0),
+    d: 5,
+  })
+
+  // This will not removed
+  macro('ld', {
+    from: new Point(10, 20),
+    to: new Point(80, 20),
+    d: 5,
+    id: 'example' // custom ID
+  })
+
+  macro('rmad')
+
+  return part
+}
+```
+</Example>