Monorepo tips

When using rnuc for a project which is a part of monorepo the following things can some handy:

Monorepo support in CLI
Specifying path to react-native build.gradle will try to find path to a folder with react-native which maybe quite problematic with monorepo. If this is true you need to specify path to react-native yourself using this snipped in your root build.gradle:
```
buildscript {
    ext {
        REACT_NATIVE_NODE_MODULES_DIR = "<prefix>/../node_modules/react-native"
    }
}
```
where <prefix> are several ../ depending on how your repo is structured. Normally this should be only two ../../ if you have the following layout of packages:
```
|-- package.json
|-- node_modules
    |-- react-native-ultimate-config
|-- packages
    |-- my_app
    |-- package1
    |-- package2
    |-- packageN
```