feat(markdown): New docs for various things

markdown/dev/reference/snippets/eyelet/en.md

@@ -0,0 +1,27 @@
+---
+title: eyelet
+---
+
+The `eyelet` snippet is used to mark an eyelet, which is a small reinforced opening or hole.
+
+It is provided by [plugin-annotations](/reference/plugins/annotations/), which is
+part of [core-plugins](/reference/plugins/core) (so it is available by default).
+
+## Example
+
+<Example caption="An example of the eyelet snippet">
+```js
+({ Point, Path, paths, Snippet, snippets, part }) => {
+
+  snippets.demo = new Snippet('eyelet', new Point(0,0))
+
+  // Prevent clipping
+  paths.diag = new Path()
+    .move(new Point(-50,-4))
+    .move(new Point(50,4))
+
+  return part
+}
+```
+</Example>
+