* doc/contributing.texi (Running Guix Before It Is Installed): Mention
how to remedy "source file ... newer than compiled" error by running
`make -j`.
Co-authored-by: jgart <jgart@dismail.de>
Co-authored-by: Julien Lepiller <julien@lepiller.eu>
Co-authored-by: Ryan Prior <rprior@protonmail.com>
Co-authored-by: Blake Shaw <blake@nonconstructivism.com>
Signed-off-by: Nicolas Goaziou <mail@nicolasgoaziou.fr>