Manual install README incomplete

When you're using the panel provided by the package management system of your distribution, then the prefix is in most cases /usr, otherwise the default prefix is /usr/local.

But nowhere in the README it is not explained howto change the prefix to /usr. It installs to /usr/local and I needed to copy the libweather.so from /usr/local//lib/blah-blah-blah to /usr/lib/blah-blah-blah