Update Doxygen configuration to allow reading common files from root folder of repositories

[AppleNinja910]

Update Doxyfile.cfg:

• INPUT = ../../include
  ../../src
  ./pages *.md
  ../../README.md
  ../../CONTRIBUTING.md
  ../../NOTICE
  ../../COPYING
  ../../LICENCE

[Ulrond]

@AppleNinja910 -> I think this is merged already am I correct?