Please add @types/react-firestore declarations to make it clearer the types of each element in the library

[leandroluk]

• react-firestore version: 1.0.1
• node version: 10.16.0
• npm (or yarn) version: 6.8.0

I use react together with typescript, for ease of typing and being native (I use VS Code) when comparing with Flow. It would be interesting to create a index.d.ts file containing the declared types of the library, so that it would be possible to make the most of the resources being created ...

I searched the types defined for the library but did not find it. I also searched within the repository itself and did not find it. I believe that if they were created, it would be possible to work more easily and clearly ...