docs: Fixes a typo in API documentation
docs: Fixes a typo in API documentation

magnetometer was incorrectly spelled magenetometer. 
The export in https://github.com/react-native-sensors/react-native-sensors/blob/master/src/sensors.js shows the correct way is magnetometer
react-native-sensors/react-native-sensors,react-native-sensors/react-native-sensors,react-native-sensors/react-native-sensors,react-native-sensors/react-native-sensors