Documentation Refresh

[prince-chrismc]

New year new docs?

This has been on my radar for a while but recent comments highlights how important it is.

Live example on my fork https://prince-chrismc.github.io/jwt-cpp/index.html and https://github.com/prince-chrismc/jwt-cpp/tree/e82643a748d2e1fdf75e0a81dd5ca8ee3ed59e42

• CMake build target to make it easier to run locally cmake . -DJWT_BUILD_DOCS=ON && cmake --build . --target jwt-docs
• Upgrade doxygen and CSS styling https://github.com/doxygen/doxygen/issues/10472
• new installation page closes #319 and address #321 comments
  • kick started updating the package managers https://github.com/spack/spack/pull/41894 https://github.com/microsoft/vcpkg/pull/35919
• add more details and snippets to some of the doxygen comments (trying to set an example)
• README is not focused towards "how do you use the library" with the supporting information on dedicated pages
  • updated print claims to match the create and verify examples in the examples

closes #319