Enable PDF and EPUB build #553

Job	Run time
sync / sync	4m 37s
check / Build docs (html)	5m 54s
check / Build docs (epub)	6m 4s
check / Lint translations	43s
check / Build docs (latex)	6m 14s
check / Check for zero-width space characters	4s
check / Build docs (pdf)	12m 53s
	36m 29s

Provide feedback