doc: Use @option for command-line options

* doc/guix.texi (Invoking guix system): Use @option instead of @code.

nar: 'with-temporary-store-file' uses a single connection

Previously the 'with-store' form was entered every time a different temporary
file was tried.  This caused there to be as many simultaneous open connections
as there were attempts, and prevented the (loop ...) call from being a tail
call.  This change fixes that.

* guix/nar.scm (with-temporary-store-file): open connection once prior to
  entering the loop.

nar: 'finalize-store-file' follows proper store lock protocol.

* guix/nar.scm (finalize-store-file): check for deletion token when acquiring
  lock, write deletion token and delete lock file before releasing lock.

Revert "services: syslog: Simplify 'start' method."

This reverts commit 4c0cc7bed3de2c0e2d3a6e95b88693941e839eec.
Fixes <https://bugs.gnu.org/41116>.
Reported by Alex Sassmannshausen <alex@komputilo.eu>.

The problem is that reconfiguring on a system running Shepherd < 0.8.0
would lead to an error, due to #:file-creation-mask not being supported.
The error is rather harmless: it prevents service upgrade but the system
itself is upgraded.

We can reinstate that commit eventually, once #:file-creation-mask has
become widespread.

guix system: 'docker-image' honors '--network'.

* gnu/system/vm.scm (system-docker-image): Add #:shared-network? and
pass it to 'containerized-operating-system'.
(qemu-image):
* guix/scripts/system.scm (system-derivation-for-action): Pass
 #:shared-network? to 'system-docker-image'.
* doc/guix.texi (Invoking guix system): Document it.

git-authenticate: Use the 'origin/keyring' branch by default.

Previously one would need to have a worktree for the local 'keyring'
branch.

Reported by reepca and bricewge on #guix.

* build-aux/git-authenticate.scm (load-keyring-from-reference): Use
'branch-lookup' instead of 'reference-lookup'.  Add "origin/" to
REFERENCE.
(authenticate-commits): Have #:keyring-reference default to "keyring".

doc: Tiny markup fix.

* doc/guix.texi (Substitute Authentication): Use @samp instead of @code for
pseudo-code.

doc: Remove markup for external package names.

* doc/guix.texi (Invoking guix import): Remove markup, which is not warranted
here.

doc: Use @file instead of @code also for file extensions.

* doc/guix.texi (Defining Packages):
(Build Systems):
(Derivations):
(Invoking guix import):
(Printing Services):
(Installing Debugging Files):
(Preparing to Use the Bootstrap Binaries): Use @file instead of @code.

doc: Use @env for environment variables.

* doc/guix.texi (Binary Installation):
(Build Environment Setup):
(Invoking guix-daemon):
(Application Setup):
(After System Installation):
(Invoking guix package):
(Proxy Settings):
(Invoking guix environment):
(Packages for C Development):
(Package Modules):
(Build Systems):
(The Store):
(Common Build Options):
(Invoking guix download):
(Invoking guix refresh):
(Using the Configuration System):
(Locales):
(Base Services):
(Networking Services):
(Sound Services):
(Continuous Integration):
(PAM Mount Service):
(X.509 Certificates): Use @env instead of @code for environment variables.

gnu: usbguard: Fix warning about 'catch'.

* gnu/packages/hardware.scm (usbguard)[arguments]: Rename phase
'patch-makefile' to 'patch-build-scripts', patch 'Makefile.in' files
instead of 'Makefile.am' and fix 'catch' include path.
[native-inputs]: Remove 'autoconf' and 'automake'.

gnu: usbguard: Use packaged 'pegtl'.

* gnu/packages/hardware.scm (usbguard)[arguments]: Remove configure flag
'--with-bundled-pegtl'.
[inputs]: Add 'pegtl'

gnu: Add pegtl.

* gnu/packages/cpp.scm (pegtl): New variable.

doc: Use @option instead of @code.

* doc/guix.texi (Binary Installation):
(Requirements):
(Build Environment Setup):
(Invoking guix-daemon):
(Application Setup):
(Invoking guix package):
(Substitute Server Authorization):
(Substitution Failure):
(Invoking guix gc):
(Invoking guix pull):
(Invoking guix archive):
(Invoking guix environment):
(Invoking guix pack):
(Defining Packages):
(Build Systems):
(The Store):
(Invoking guix build):
(Common Build Options):
(Package Transformation Options):
(Additional Build Options):
(Debugging Build Failures):
(Invoking guix edit):
(Invoking guix import):
(Invoking guix refresh):
(Invoking guix lint):
(Invoking guix publish):
(Invoking guix challenge):
(Base Services):
(Virtualization Services):
(Initial RAM Disk):
(Invoking guix system):
(Preparing to Use the Bootstrap Binaries):
(Porting): Use @option instead of @code for command-line options.

doc: Fix typo in container example.

* doc/guix.texi (Invoking `guix environment'): Fix sll -> ssl typo.

doc: Add container example to run a web browser.

* doc/guix.texi (Invoking `guix environment'): Add paragraph and example to
  run Eolie in a guix environment container.  Add `container' cindex for the
  first container example, and the `certificates' cindex for the web browser
  example.

gnu: warsow-qfusion: Remove bundled binaries and inputs.

* gnu/packages/game-development.scm (warsow-qfusion)[source]: Add snippet to
  remove unused bundled binaries and inputs.

gnu: sbcl-iolib.grovel: Deprecate in favour of sbcl-cffi-grovel.

* gnu/packages/lisp-xyz.scm (sbcl-iolib.grovel): Deprecate since upstream has
  removed it; they are now using cffi-grovel instead.

gnu: sbcl-trivial-backtrace: Fix typo in description.

* gnu/packages/lisp-xyz.scm (sbcl-trivial-backtrace)[description]: Replace
  "On" with "One".

gnu: glibc/hurd-headers: Cross-build fix for the Hurd.

* gnu/packages/base.scm (glibc/hurd-headers)[native-inputs]: Add mig; when
cross-building use 32-bit mig.