Adding documentation for the STOMMS

[usmanriaz07]

This PR:

• adds a Doxygen document for the APIs.
• adds a Sphinx html document for main documentation.
  • General Information
  • Installation and Testing
  • Input Parameters
  • Output Files
  • Basic APIs user documentation for stomms_reader
  • Contact Information
• a github workflow for the automatic updates
• For changes in stomms_meshgen doc, work with Doxygen source file STOMMS/stomms_meshgen/meshgen.dox
• For changes in stomms_reader doc, work with Doxygen source file STOMMS/stomms_reader/reader.dox
• Top level Doxygen file STOMMS/docs/doxygen_mainpage.md and STOMMS/docs/dDoxyfile.in
• Top level Sphinx file STOMMS/docs/source/index.rst
• The APIs for tokamak version (eqdsk) are not fully commented (as of 04/22/2026), I will keep adding comments to them in a new branch to make sure they have proper documentation.