For release/1.8.0: update S4 site config and documentation

[climbfuji]

Summary

Update S4 site config and documentation (readthedocs) for S4 after the Rocky 8 update. For spack-stack-1.8.0. Will retag release/1.8.0 as spack-stack-1.8.0 once this PR and #1326 are merged.

See #1329 for follow-up changes for spack-stack-1.9.0.

Testing

Installed ue-intel-2021.10.0 in test environment, official install running. Will update Wiki after the jedipara installation is complete.

Built jedi-bundle (didn't run all ctests, that is for JCSDA)

Applications affected

n/a

Systems affected

S4

Dependencies

n/a

Issue(s) addressed

Working towards #1278

Checklist

• This PR addresses one issue/problem/enhancement, or has a very good reason for not doing so.
• These changes have been tested on the affected systems and applications.
• All dependency PRs/issues have been resolved and this PR can be merged.

[climbfuji]

@InnocentSouopgui-NOAA @eap FYI

[DavidHuber-NOAA]

Just a couple of path updates, but otherwise it looks good.

[InnocentSouopgui-NOAA]

Please, also install spack-stack-1.6.0 fore Rocky 8 on S4.
S4 has users who need spack-stack-1.6.0 to finish research experiments they already started before the upgrade of the OS.

[climbfuji]

Installation in official location as jedipara was successful, I updated https://github.com/JCSDA/spack-stack/wiki/spack%E2%80%90stack%E2%80%901.8.0-release-documentation.

[climbfuji]

Please, also install spack-stack-1.6.0 fore Rocky 8 on S4. S4 has users who need spack-stack-1.6.0 to finish research experiments they already started before the upgrade of the OS.

Finishing experiments with an entirely different software environment (even though it is spack-stack-1.6.0, but different compilers, OS libraries, ...) sounds like a bad idea.

Either way, JCSDA will be taking care of this when they have time. I volunteered to update the site config for JCSDA for spack-stack-1.8.0 in my free time on the weekend.

Also, users who don't want to wait are welcome to check out the release branch for spack-stack-1.6.0, update the S4 site config from the spack-stack-1.8.0 release branch, and install the updated spack-stack environment in their own space.

[DavidHuber-NOAA]

Looks good, thanks @climbfuji!