Add Troubleshooting section to README
Add Troubleshooting section to README

I've researched the most common issues in the repository. Mostly all of them are related to incorrect installation
Added some basic troubleshooting suggestions to a dedicated README section

Related to: #360
react-native-community/react-native-linear-gradient,react-native-community/react-native-linear-gradient,react-native-community/react-native-linear-gradient,react-native-community/react-native-linear-gradient