gnu: Update module imports for asciidoc and doxygen.

gnu: Update module imports for asciidoc and doxygen.

This is a followup to commit 0573a923def01e54bf104e0015ade44ab42f694f.

* gnu/packages/algebra.scm, gnu/packages/bioinformatics.scm,
gnu/packages/fcitx.scm, gnu/packages/fish.scm,
gnu/packages/freedesktop.scm, gnu/packages/game-development.scm,
gnu/packages/gcc.scm, gnu/packages/graphics.scm, gnu/packages/image.scm,
gnu/packages/kodi.scm, gnu/packages/libreoffice.scm,
gnu/packages/linux.scm, gnu/packages/messaging.scm,
gnu/packages/mpd.scm, gnu/packages/music.scm, gnu/packages/rdf.scm,
gnu/packages/serialization.scm, gnu/packages/version-control.scm,
gnu/packages/web.scm, gnu/packages/wm.scm, gnu/packages/xdisorg.scm,
gnu/packages/xiph.scm: Change imports of (gnu packages asciidoc) or
(gnu packages doxygen) to (gnu packages documentation).