doc: Fix minor typos.

doc: Fix minor typos.

* doc/guix.texi (cargo-build-system): Fix install phase description.
(julia-build-system): Fix typo and add information from check.
(pulseaudio-configuration): Remove duplicated words.
(knot-acl-configuration)[id]: Fix typo.
(mpd-output)[extra-options]: Likewise.
(libvirt-configuration) [listen-tls?]: Add missing subject.
[listen-tcp?]: Add missing subject and period.
[tls-port, tcp-port, log-filters]: Add missing period.
(hurd-vm-configuration)[netoptions]: Fix typo in example.
(ganeti-watcher-service-type): Fix typo.
(grub-theme)[gfxmode]: Remove see before @pxref.