Add types to exports in package.json

[Joristdh]

When using your package in our (module) project, I get the following error:

Could not find a declaration file for module 'react-use-print'. '/node_modules/react-use-print/dist/react-use-print.es.js' implicitly has an 'any' type.
There are types at '/node_modules/react-use-print/dist/index.d.ts', but this result could not be resolved when respecting package.json "exports". The 'react-use-print' library may need to update its package.json or typings.

This can be resolved by adding the typing information to the exports property in the package.json.