Missing instructions on how to make appear files into "File" app on iOS (with fix)

The thing is pretty straightforward. The guides on how to use RNFS do not explain carefully that **iOS hides by default the files that you save**. Every app in iOS has its "sandbox" when they can write/read without any major restrictions, but by default users aren't able to see any files. This could be potentially a problem if saved files are needed for the final user.

On Android this problem does not exist, since you can write, for example, in `Download` folder, if storage access is granted.

This was very unclear for me: the functions as `write` or `exists` was working: they both was returning `ok` when finishing saving or checking if file exists, but I couldn't see the files in the `File` app. Since I have some apps installed on my device, I saw that everyone has his folder inside `on My iPhone` but mine didn't.

After 2 days spending on understanding what permissions do I need or what I'm doing wrong, I discovered that **you need to explicitly indicate to iOS that your app is able to "expose" internal files**, in order to make it visible inside `File` app. Solution is very easy: just add this lines into your `info.plist` file (located in ios folder in your react-native project):

```

....
UIFileSharingEnabled

LSSupportsOpeningDocumentsInPlace

UISupportsDocumentBrowser

```

This will indicate that your app is exposing file saved inside `RNFS.DocumentDirectoryPath` and user can access them with the `File` app.

It would be great to add this instruction to README.