Remove links to the internal GitHub repository for files

[k1nshuk]

Some of the documentation leverages files that are not accessible by the broader audience outside of NREL. For example in the following file:

https://github.com/NREL/HPC/blob/master/general/intermediate/software-environment-basics/conda-how-to.md

It would make sense to make those files available here and also update the documentation to remove references to Peregrine or other older systems.

[yandthj]

@harrysorensennrel Can you work with Kinshuk to migrate these files to the public github?