bug#69123: Guix manual returns a 404 when trying to download FiraSans-Regular.ttf

[Balthazar Potet]

When accessing the manual at https://guix.gnu.org/manual/en/guix.html,
the FiraSans font fails to download from
https://guix.gnu.org/static/base/fonts/FiraSans-Regular.ttf.
As a result, the text is displayed in bold.