doc: fetch DocBook XSL from cdn.docbook.org
This now uses HTTPS, and uses hopefully a more future-proof URL instead of SourceForge.
We use DocBook 4.x so use xsl-nons/.
Signed-off-by: Simon Ser contact@emersion.fr
This now uses HTTPS, and uses hopefully a more future-proof URL instead of SourceForge.
We use DocBook 4.x so use xsl-nons/.
Signed-off-by: Simon Ser contact@emersion.fr