Updated iOS Upgrading Guide for 3.2.0 (trivial - same as previous)
CB-5432: Correct docs for splash screen

- The config.xml example was malformed. Fix it.
- Add more explanation about using splashscreen on Android.
- Explain that invoking splashscreen.show() is probably not desired.
CB-5432: fix typos in config.xml example in 3.1
CB-5432: fix a non-functional typo
redo CB-5122 pull request 140
updated upgrading guides to include 3.2.0
Version 3.2.0
Expect FileError when requestFileSystem or resolveLocalFileSystemURI fails