readme should mention that appAuthRedirectScheme must be lowercased for application be able to catch authorization redirect (#659)

Author: Dergash

README.md

@@ -410,7 +410,7 @@ android {
 ```
 
 The scheme is the beginning of your OAuth Redirect URL, up to the scheme separator (`:`) character. E.g. if your redirect uri
-is `com.myapp://oauth`, then the url scheme will is `com.myapp`.
+is `com.myapp://oauth`, then the url scheme will is `com.myapp`. The scheme must be in lowercase.
 
 NOTE: When integrating with [React Navigation deep linking](https://reactnavigation.org/docs/deep-linking/#set-up-with-bare-react-native-projects), be sure to make this scheme (and the scheme in the config's redirectUrl) unique from the scheme defined in the deep linking intent-filter. E.g. if the scheme in your intent-filter is set to `com.myapp`, then update the above scheme/redirectUrl to be `com.myapp.auth` [as seen here](https://github.com/FormidableLabs/react-native-app-auth/issues/494#issuecomment-797394994).