Fix instruction in README

[MariuszSkamra]

This fixes the missing mention of the RALib dependency. Since "mvn install" fails due to RALib missing, the instruction is updated to use the ./install.sh script, which handles the dependency automatically.

[kostis]

Thanks for your interest in ProtocolState-Fuzzer and for your PR!

You are correct that the RALib dependency is nowhere mentioned in the README and mvn install fails due to that. We are aware of this problem and, for that reason, ProtocolState-Fuzzer nowadays comes with an install script that you can use instead of mvn install. Let us know if you encounter any problem when using this. (Yes, we are also aware that this is nowhere mentioned.)

Although we appreciate your PR, I will leave this unmerged and open for a while, because the proper fix here is not to update ProtocolState-Fuzzer's README to mention the above (this is a correct temporary fix), but to add RALib into maven and update the pom.xml to get it from there. (This has been on our TODO list, for quite a while now, but has not happened yet due to a variety of reasons... Hopefully, it will happen soon. I will move it higher on the list of my priorities.)

Thanks again for your interest in PSF. Let us know about your experiences and feel free to open more issues/PRs in case you notice anything else that requires fixing or is not according to your needs.