how can users test the installation

Add instructions about how to test if the installation is working, by compiling an example code for example.

From Rob: What I did was download the Megachiropteran binary tools repo, copy the installed
rose-config.cfg file to the tool source tree, and ran "make install". Unfortunately the megachiropteran repo is not public, thus not suitable for public instruction, but its makefile is basically like what we came up with some months ago for external tools.