docs: updating old hyperlinks from using NREL to NatLabRockies in docs.

[estebanpuyanas]

Pull Request Template

Description

Docs like README.md and CONTRIBUTING.md have hyperlinks using the previous GitHub org name of NREL. This PR is updating relevant links to use NatLabRockies.

While I confirmed that links using NREL still work, I believe this change to use current org name formalizes expectations for writing and maintaining documentation.

Fixes # (issue(s))
N/A. No open issues with this title or description.

Corresponding branches and PRs:

[ which branches of wex, lk, and ssc should be built with this PR ]
Development.

[ link any corresponding PRs in other repos, i.e. NREL/ssc#x ]
N/A.

Unit Test Impact:

N/A.

Checklist

• requires help revision and I added that label
• adds, removes, modifies, or deletes variables in existing compute modules
• adds a new compute module
• changes defaults
• I've tagged this PR to a milestone

N/A (?) this is just a docs maintenance PR.

[brtietz]

Thanks for updating!