add migration guide

Author: jscottsmith

README.md

@@ -4,7 +4,7 @@
 
 React components to create parallax scroll effects for banners, images or any other DOM elements. Uses a single scroll listener via [Parallax Controller](https://github.com/jscottsmith/parallax-controller) to add vertical or horizontal scrolling based offsets to elements based on their position in the viewport. [Optimized](https://github.com/jscottsmith/parallax-controller#optimizations-to-reduce-jank) to _reduce_ jank on scroll and works with universal (server-side rendered) React apps.
 
-If you're coming from [v1](https://github.com/jscottsmith/react-scroll-parallax/tree/v1), here's a [migration guide](https://github.com/jscottsmith/react-scroll-parallax/blob/master/docs/migration-guide.md).
+If you're coming from [V2](https://github.com/jscottsmith/react-scroll-parallax/tree/v2.4.2), here's a [migration guide](https://github.com/jscottsmith/react-scroll-parallax/blob/master/docs/migration-guide.md).
 
 ## Examples
 

docs/migration-guide.md

@@ -1,4 +1,41 @@
-# Migration Guide
+# V2 Migration Guide
+
+With mostly just new features, V3 also makes a few breaking changes. See the following and migrate any code that is affected.
+
+### Renamed Props
+
+If you've used any of the following props simply rename to the new ones.
+
+1. `styleOuter` becomes `style`.
+2. `tagOuter` becomes `tag`.
+3. `x` becomes `translateX`.
+4. `y` becomes `translateY`.
+
+### Using the context hook.
+
+The hook to access the parallax controller is now returned directly.
+
+If you used the following:
+
+```js
+const { parallaxController } = useController();
+```
+
+change it to:
+
+```js
+const parallaxController = useController();
+```
+
+### Removed default class names
+
+If you relied on either the `parallax-outer` or `parallax-inner` class names for styling you will need to explicitly define them.
+
+```jsx
+<Parallax className="parallax-outer" innerClassName="parallax-inner" />
+```
+
+# V1 Migration Guide
 
 Some breaking changes were introduced in v2. Here's the simple changes that need to be made if you're coming from v1.