Untranslatable string in Epiphany

[Michael Catanzaro <mcatanzaro gnome org>]

Hi translators,

I've just marked a missing string for translation after it was reported 
in https://gitlab.gnome.org/GNOME/epiphany/-/issues/1478. This string 
is "Without Sound," used to indicate that videos with no sound have 
permission to autoplay. It has existed since 3.38, it just hadn't been 
reported until now. :(

Sorry about this,

Michael