docs(datafile manager): Removed manual dependency installation requirement from docs (#457)

Datafile Manager does not require manual installation of @react-native-community/async-storage dependency as this is now added as a dev dependency and will automatically be installed

Author: zashraf1985

packages/datafile-manager/README.md

@@ -36,11 +36,6 @@ manager.on('update', ({ datafile }) => {
 ```
 
 ## Development
-For development, installation of peer dependency `@react-native-community/async-storage` is also required:
-```sh
-npm i --no-save @react-native-community/async-storage
-```
-
 - The `lint` package.json script runs ESLint and Prettier. This applies formatting and lint fixes to all `.ts` files in the `src/` directory.
 - The `test` package.json script runs our Jest-based test suite.
 - The `tsc` package.json script runs the TypeScript compiler to build the final scripts for publishing (into the `lib/` directory).