Fixes <https://issues.guix.gnu.org/58813>. No longer suggests to splice the
output of etc/teams.scm commands into the 'git send-email' command line; this
is now transparently handled by the Git configuration, which is also
automatic.
* doc/contributing.texi (Configuring Git): Streamline section, now automated
via Automake.
(Sending a Patch Series): Do not specify options configured as default by the
above. Prefer long option names, for readability.
(Teams): Rewrite the examples to use --header-cmd.
(Commit Access): Refer to the Configuring Git section instead of detailing
manual steps.
1d77fd705b