README.md: update with link to doxygen documentation

[MatthewMasarik-NOAA]

Pull Request Summary

Adds a link to the develop README.md for doxygen documentation.

Description

• Provide a detailed description of what this PR does.
  • A link is added to the develop branch README.md, which points to the html doxygen generated webpages for WW3.
• What bug does it fix, or what feature does it add?
  • N/A.
• Is a change of answers expected from this PR?
  • No.

Please also include the following information:

• Add any suggestions for a reviewer
  • @JessicaMeixner-NOAA
• Mention any labels that should be added:
  • documentation
• Are answer changes expected from this PR? Please describe the changes and the reason why in addition to which of the following labels would apply: mod_def change, out_grd change, out_pnt change, restart file change, Regression test
  • N/A.

Issue(s) addressed

• Please list any issues associated with this PR, including those the PR will fix/close. For example:
  • Does not fix any issues, though does address reviewer request: Host doxygen html output on github pages #1286 (comment)

Commit Message

README.md: update with link to doxygen documentation

Check list

• Branch is up to date with the authoritative repository (NOAA-EMC) develop branch.
• Checked the checklist for a developer submitting to develop.
• [na] If a version number update is required, checked the updating version number checklist.
• [na] If a new feature was added, a regression test for testing the new feature is added.

Testing

• How were these changes tested?
  • N/A (documentation only).
• Are the changes covered by regression tests? (If not, why? Do new tests need to be added?)
  • No code changes.
• Have the matrix regression tests been run (if yes, please note HPC and compiler)?
  • N/A
• Please indicate the expected changes in the regression test output, (Note the list of known non-identical tests.)
  • N/A
• Please provide the summary output of matrix.comp (matrix.Diff.txt, matrixCompFull.txt and matrixCompSummary.txt):
  • N/A

[JessicaMeixner-NOAA]

Thanks for updating the readme @MatthewMasarik-NOAA and for the work towards doxygen!

[JessicaMeixner-NOAA]

No testing is done as this is just an update to the readme.