Update README

[uqmessias]

Since a migration from js to ts is in progress, we'll need to update the README with newer instructions like not linking the library for some versions of RN.

Also, we need to properly document the Component Props and use cases.

[uqmessias]

In fact, I'm not sure if this is needed (at least for future use) because since the react-native-svg@v7.0.0 you can use SvgUri and SvgXml directly from there.

It was originally requested in this issue