Fix README method signatures #16
Description
In the current version of the README (that appears to not have been edited in 5 years) there seems to be an error in the first example, where the FFmpegInput constructor is shown to take an InputStream as its only parameter opposed to a single instance of FFmpegIO as shown in the latter example.
This can easily lead people who only read the basic example to confusion, especially when paired with the (as far as I know) complete lack of any documentation for the java implementation.