wip: Working on better developer docs

markdown/dev/reference/api/pattern/on/en.md

@@ -1,15 +1,41 @@
 ---
-title: on()
+title: Pattern.on()
 ---
 
+A pattern's `on()` method allows you to attach a function to one of the 
+pattern's [lifecycle hooks](/reference/hooks/). It takes the
+lifecycle hook's name as the first argument and the function as the second.
+This method will then be triggered by the lifecycle hook.
+
+<Note>Since FreeSewing v2.19, this method is chainable as it returns the Pattern object</Note>
+
+## Pattern.on() signature
+
 ```js
-void pattern.on(string hook, function method)
+Pattern pattern.on(string hook, function method)
 ``` 
 
-Allows you to attach a method to one of our hooks. 
+<Tip>
 
-Takes the hook name as a first argument, and your method as a second.
+Refer to [the Lifecycle hooks documentation](/reference/hooks/) for a list
+of all avaialble lifecycle hooks, as well as the signature of the function you
+should pass it.
 
-See [extending freesewing](/extend/) for details about extending freesewing with hooks.
+</Tip>
+
+## Pattern.on() example
+
+```js
+pattern.on('preRender', function(svg) {
+  svg.style += "svg { background: yellow;}";
+})
+```
+
+Your pattern now has a yellow background.
+
+<Tip>
+
+The [plugin guide](/guides/plugins/) contains more info on how you can use hooks
+
+</Tip>
 
-<Fixme>Code example</Fixme>