CompilingOnLinux Guide: Fixes path erros and removes unnecessary sudos; ...

...Adds instruction to walkaround (q)axcontainer problem.

There is no need to compile as superuser and afaik there is no need to run gridcoin-qt as super user. To prevent security issues this instructions are changed. Also some of the paths were wrong or used the wrong case (and most file systems used on linux are case-sensitiv).