gnu: Fix descriptions to not use quotes.

* gnu/packages/admin.scm (wpa-supplicant-minimal, mingetty, di),
* gnu/packages/audio.scm (fil-plugins),
* gnu/packages/base.scm (make-ld-wrapper, make-glibc-locales),
* gnu/packages/bioinformatics.scm (r-samtools),
* gnu/packages/chez.scm (chez-mit),
* gnu/packages/commencement.scm (make-gcc-toolchain),
* gnu/packages/compression.scm (fastjar),
* gnu/packages/cran.scm (r-maps, r-rcpp),
* gnu/packages/databases.scm (sparql-query),
* gnu/packages/dunst.scm (dunst),
* gnu/packages/ftp.scm (ncftp),
* gnu/packages/gl.scm (freeglut),
* gnu/packages/haskell-check.scm (ghc-tasty-golden),
* gnu/packages/haskell.scm (ghc-case-insensitive, ghc-text,
ghc-haskell-src, ghc-syb, ghc-deepseq-generics, ghc-network-uri,
ghc-rerebase, ghc-zlib),
* gnu/packages/image.scm (jbig2dec),
* gnu/packages/kde-frameworks.scm (kinit, karchive),
* gnu/packages/linux.scm (wireless-tools, perf, module-init-tools, kbd),
* gnu/packages/lirc.scm (lirc),
* gnu/packages/lisp.scm (uglify-js),
* gnu/packages/mate.scm (mate-netbook),
* gnu/packages/microcom.scm (microcom),
* gnu/packages/music.scm (bristol),
* gnu/packages/networking.scm (perl-geo-ip),
* gnu/packages/patchutils.scm (patches),
* gnu/packages/perl-check.scm (perl-test-more-utf8),
* gnu/packages/perl.scm (perl-log-report-optional, perl-file-which,
perl-io-tty, perl-log-any, perl-digest-sha1, perl-class-load,
perl-regexp-common, perl-module-pluggable, perl-class-modifier),
* gnu/packages/python-xyz.scm (python-backports-abc, python-natsort),
* gnu/packages/samba.scm (iniparser),
* gnu/packages/search.scm (mlocate),
* gnu/packages/spice.scm (spice),
* gnu/packages/statistics.scm (r-dt, r-lubridate, r-estimability,
r-commonmark, r-digest, r-viridislite, r-stringr),
* gnu/packages/tex.scm (texlive-latex-changebar),
* gnu/packages/version-control.scm (subversion),
* gnu/packages/w3m.scm (w3m),
* gnu/packages/web.scm (perl-http-parser,
perl-plack-middleware-reverseproxy),
* gnu/packages/xorg.scm (xkeyboard-config, mkfontdir, xcursor-theme,
mkfontscale, xinit, font-alias)[description]: Use @code instead of quotes.

gnu/packages/dunst.scm

@@ -73,6 +73,6 @@
     (synopsis "Customizable and lightweight notification daemon")
     (description
      "Dunst is a highly configurable and minimalistic notification daemon.
-It provides 'org.freedesktop.Notifications' D-Bus service, so it is
+It provides @code{org.freedesktop.Notifications} D-Bus service, so it is
 started automatically on the first call via D-Bus.")
     (license license:bsd-3)))