[website][docs] Include class methods in generated docs

[mkonicek]

For example DrawerLayoutAndroid has the method openDrawer:
https://github.com/facebook/react-native/blob/master/Libraries/Components/DrawerAndroid/DrawerLayoutAndroid.android.js

But we only generate docs for propTypes:
https://facebook.github.io/react-native/docs/drawerlayoutandroid.html#content

[janicduplessis]

I'll work on this this week :)

[janicduplessis]

Done in #6890

[janicduplessis]

@facebook-github-bot close

[facebook-github-bot]

@janicduplessis tells me to close this issue. If you think it should still be opened let us know why.