Improve EventLoaderEUDAQ2 README
As the title says.
These changes/improvents are inspired by Mateus' experience with installing Corryvreckan on LXPLUS (and other people before him, e.g. at the BTTB8 tutorials). They add more details/tips on how to install with EUDAQ2 and Peary. In particular, it is pointed out that it is important to make sure to compile everything with the same compiler version.
Plus a few typo fixes.