Correct documentation build failures & reflect switch to spack-stack

[gspetro-NOAA]

PR Author Checklist:

• I have linked PR's from all sub-components involved in section below. (N/A)
• I am confirming reviews are completed in ALL sub-component PR's. (N/A)
• I have run the full RT suite on either Hera/Cheyenne AND have attached the log to this PR below this line:
  • LOG: N/A - No tests required for documentation updates.
• I have added the list of all failed regression tests to "Anticipated changes" section. (N/A)
• I have filled out all sections of the template.

Description

This PR updates the documentation with information about the WM switch to spack-stack.
This PR also cures documentation build fails on ReadTheDocs.
See the docs build from my fork here: https://gsp-wm.readthedocs.io/en/text-release-doc/
Build passed:

Linked Issues and Pull Requests

Closes Issue #1949 and #1951.

Subcomponent Pull Requests

N/A

Blocking Dependencies

N/A

Subcomponents involved:

• AQM
• CDEPS
• CICE
• CMEPS
• CMakeModules
• FV3
• GOCART
• HYCOM
• MOM6
• NOAHMP
• WW3
• stochastic_physics
• none

Anticipated Changes

Input data

• No changes are expected to input data.
• Changes are expected to input data:
  • New input data.
  • Updated input data.

Regression Tests:

• No changes are expected to any regression test.
• Changes are expected to the following tests:

None

Libraries

• Not Needed
• Needed
  • Create separate issue in JCSDA/spack-stack asking for update to library. Include library name, library version.
  • Add issue link from JCSDA/spack-stack following this item

Code Managers Log

• This PR is up-to-date with the top of all sub-component repositories except for those sub-components which are the subject of this PR.
• Move new/updated input data on RDHPCS Hera and propagate input data changes to all supported systems.
  • N/A

Testing Log:

• RDHPCS
  • Hera
  • Orion
  • Hercules
  • Jet
  • Gaea
  • Cheyenne
• WCOSS2
  • Dogwood/Cactus
  • Acorn
• CI
  • Completed
• opnReqTest
  • N/A
  • Log attached to comment

[jkbk2004]

merged with #1923