Doc: @snippets links are broken when translated

[Valentin Villenave]

Greetings everybody,

some translated doc pages have broken @snippet links; for example if
you follow the link at the bottom of
http://lilypond.org/doc/v2.15/Documentation/notation/expressive-marks-as-curves.de.html
you'll see that it points to
http://lilypond.org/doc/v2.15/Documentation/snippets/ausdrucksbezeichnungen
which doesn't exist (node names are not supposed to be translated in URLs).

However, this isn't the case in other sections: for example at the bottom of
http://lilypond.org/doc/v2.15/Documentation/notation/piano.fr.html
It points to the right address:
http://lilypond.org/doc/v2.15/Documentation/snippets/keyboards

Cheers,
Valentin.