Update README to use relative nsys command paths

[lsawade]

Thanks for making this, Jon!

The /usr/local/bin/nsys was using the wrong executable after loading the cudatoolkit. Removing /usr/local/bin/ solves the issues.

[jdh4]

The idea is to use the full path:
https://researchcomputing.princeton.edu/support/knowledge-base/gpu-computing#Profiling

This allows the latest nsys to be used for users that load an older CUDA toolkit. Doesn't loading the module cause you to use the nsys in that module and not the system version when full path is not applied? We can update the system nsys. Usually do this before the hackathon.

[lsawade]

Sorry, only saw the reply now. The problem was when you use a new cudatoolkit to run the profiles. You cannot read them with the older nsys. I tried several different version combinations.