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/linux.scm

@@ -1996,7 +1996,7 @@ system.")
     (description
      "This package contains keytable files and keyboard utilities compatible
 for systems using the Linux kernel.  This includes commands such as
-'loadkeys', 'setfont', 'kbdinfo', and 'chvt'.")
+@code{loadkeys}, @code{setfont}, @code{kbdinfo}, and @code{chvt}.")
     (license license:gpl2+)))
 
 (define-public loadkeys-static
@@ -2302,7 +2302,7 @@ mapper.  Kernel components are part of Linux-libre.")
        #:tests? #f))
     (synopsis "Tools for manipulating Linux Wireless Extensions")
     (description "Wireless Tools are used to manipulate the now-deprecated
-Linux Wireless Extensions; consider using 'iw' instead.  The Wireless
+Linux Wireless Extensions; consider using @code{iw} instead.  The Wireless
 Extension was an interface allowing you to set Wireless LAN specific
 parameters and get the specific stats.  It is deprecated in favor the nl80211
 interface.")
@@ -2660,7 +2660,7 @@ in a digital read-out.")
 with support in the Linux kernel.  perf can instrument CPU performance
 counters, tracepoints, kprobes, and uprobes (dynamic tracing).  It is capable
 of lightweight profiling.  This package contains the user-land tools and in
-particular the 'perf' command.")
+particular the @code{perf} command.")
     (license (package-license linux-libre))))
 
 (define-public pflask
@@ -4016,8 +4016,8 @@ the default @code{nsswitch} and the experimental @code{umich_ldap}.")
     (home-page "https://www.kernel.org/pub/linux/utils/kernel/module-init-tools/")
     (synopsis "Tools for loading and managing Linux kernel modules")
     (description
-     "Tools for loading and managing Linux kernel modules, such as `modprobe',
-`insmod', `lsmod', and more.")
+     "Tools for loading and managing Linux kernel modules, such as
+@code{modprobe}, @code{insmod}, @code{lsmod}, and more.")
     (license license:gpl2+)))
 
 (define-public mcelog