[feature] V2 Migration Guide

**Is your feature request related to a problem? Please describe.**
We would like to migrate to the latest version of this package (2.x.x) but there is no migration guide and we can't find any examples of how to use the new components with "composition" and move away from class inheritance .

**Describe the solution you'd like**
A V1 to V2 migration guide or some clear examples of how to use features such as Page and ResponsiveGrid

**Describe alternatives you've considered**
We have trawled through changelogs, release logs, PRs and unit tests but it is still not clear how to migrate from V1 effectively

**Additional context**
As a direct example, how would we pass the author components down, like we do for class components with "this.childComponents"

```
class GenericCmsPage extends Page {
render() {
...
{this.childComponents}
...
}
}
```