fix(markdown): Restructure part reference. See #2981

markdown/dev/reference/api/part/sethidden/en.md

@@ -0,0 +1,32 @@
+---
+title: Part.setHidden()
+---
+
+The `Part.setHidden()` method will mark the part either hidden
+or not, depending on the value you pass it.
+This method returns the `part` object, so it's chainable
+
+- Pass a *truthy* value: The part will be hidden
+- Pass a *falsy* value: The part will be unhidden/revealed
+
+<Tip>
+This method can be destructured as `setHidden` 
+in [a part's draft method](/reference/api/part/draft).
+</Tip>
+
+<Related>
+
+The [hide](/reference/api/part/hide) and
+[unhide](/reference/api/part/unhide) also control a
+part's visibility
+
+</Related>
+
+## Part.setHidden() example
+
+```js
+cont part = {
+  name: 'examples.hide',
+  draft: ({ setHidden, part }) =>  part.setHidden(true)
+}
+```