Document `init` hook

README.md

@@ -152,6 +152,7 @@ desired points in the life of a virtual node.
 | Name        | Triggered when                                     | Arguments to callback   |
 | ----------- | --------------                                     | ----------------------- |
 | `pre`       | the patch process begins                           | none                    |
+| `init`      | a vnode has been added                             | vnode                   |
 | `create`    | a DOM element has been created based on a VNode    | `emptyVNode, vnode`     |
 | `insert`    | an element has been inserted into the DOM          | `vnode`                 |
 | `prepatch`  | an element is about to be patched                  | `oldVnode, vnode`       |
@@ -165,7 +166,7 @@ The following hooks are available for modules: `pre`, `create`,
 `update`, `destroy`, `remove`, `post`.
 
 The following hooks are available in the `hook` property of individual
-elements: `create`, `insert`, `prepatch`, `update`, `postpatch`,
+elements: `init`, `create`, `insert`, `prepatch`, `update`, `postpatch`,
 `destroy`, `remove`.
 
 #### Usage
@@ -182,6 +183,15 @@ h('div.row', {
 });
 ```
 
+#### The `init` hook
+
+This hook is invoked during the patch process when a new virtual node has been
+found. The hook is called before Snabbdom has processed the node in any way.
+I.e. before at has created a DOM node based on the vnode.
+
+If the hook handler sets the `vnode` property on the vnode when Snabbdom will
+use the vnode at `vnode` instead of the actual vnode.
+
 #### The `insert` hook
 
 This hook is invoked once the DOM element to a vnode has been inserted into the