Minor javadoc comment for FileSystemProvider

[Ben Horowitz]

Hi,

In the javadoc for java.nio.file.spi.FileSystemProvider:

    "may be it overridden if the system property is
java.nio.file.spi.DefaultFileSystemProvider is set" should probably be
"it may be overridden if the system property
java.nio.file.spi.DefaultFileSystemProvider is set".

Regards,
Ben