fix doxygen & gh-pages

[slspencer]

fixed: doxygen & gh-pages

[what-the-diff]

PR Summary 🌟

• Folder property update in GitHub workflow
  The folder property in the CI workflow is updated, and a target_folder property has been added for better organization! 📁
• Removal of unnecessary files
  Unneeded files (docs/doxygen/index.html and docs/doxygen/test.txt) have been removed, keeping the repository clean! 🧹
• Helpful comments added in main.cpp files
  Comment blocks have been added in src/app/seamly2d/main.cpp and src/app/seamlyme/main.cpp to provide clarity and guidance for future contributors! 💡

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[slspencer]

updated ci.yml and Doxyfile to generate to docs, not docs/doxygen, so the following error occurs during this build, but the next build should work.

Run touch docs/doxygen/.nojekyll
##[debug]/usr/bin/bash --noprofile --norc -e -o pipefail /home/runner/work/_temp/a98489eb-87c0-4c43-a61f-2058554f57e6.sh
touch: cannot touch 'docs/doxygen/.nojekyll': No such file or directory

[csett86]

If the error occurs during this build, it will occur in all builds, afaik. I will fix it