[skip ci] Autogenerate README file.

README.md

@@ -12,9 +12,9 @@ thing! https://github.com/PolymerLabs/tedium/issues
 
 -->
 
-[![Build Status](https://travis-ci.org/PolymerElements/paper-dialog-scrollable.svg?branch=master)](https://travis-ci.org/PolymerElements/paper-dialog-scrollable)
+[![Build status](https://travis-ci.org/PolymerElements/paper-dialog-scrollable.svg?branch=master)](https://travis-ci.org/PolymerElements/paper-dialog-scrollable)
 
-_[Demo and API Docs](https://elements.polymer-project.org/elements/paper-dialog-scrollable)_
+_[Demo and API docs](https://elements.polymer-project.org/elements/paper-dialog-scrollable)_
 
 
 ##<paper-dialog-scrollable>
@@ -42,4 +42,35 @@ indicating there is more content above. It shows a bottom divider if it is scrol
 the last child in its parent container, indicating there is more content below. The bottom divider
 is hidden if it is scrolled to the bottom.
 
+If `paper-dialog-scrollable` is not a direct child of the element implementing `Polymer.PaperDialogBehavior`,
+remember to set the `dialogElement`:
+
+```html
+<paper-dialog-impl id="myDialog">
+  <h2>Header</h2>
+  <div class="my-content-wrapper">
+    <h4>Sub-header</h4>
+    <paper-dialog-scrollable>
+      Lorem ipsum...
+    </paper-dialog-scrollable>
+  </div>
+  <div class="buttons">
+    <paper-button>OK</paper-button>
+  </div>
+</paper-dialog-impl>
+
+<script>
+  var scrollable = Polymer.dom(myDialog).querySelector('paper-dialog-scrollable');
+  scrollable.dialogElement = myDialog;
+</script>
+```
+
+### Styling
+
+The following custom properties and mixins are available for styling:
+
+| Custom property | Description | Default |
+| --- | --- | --- |
+| `--paper-dialog-scrollable` | Mixin for the scrollable content | {} |
+