PDF output: do not display date on cover page

Insert empty LaTeX date command.

Signed-off-by: Olivier Carrère <carrereo@gmail.com>
Acked-by: Angela Cristina <acristina@redaction-technique.org>
conf.py: fix indentation

Insert tabs to indent code.

Signed-off-by: Olivier Carrère <carrereo@gmail.com>
Acked-by: Angela Cristina <acristina@redaction-technique.org>
PDF output: display version on cover page

Insert release in conf.py.

Release may also appear in HTML and other outputs, depending on selected theme.

Signed-off-by: Olivier Carrère <carrereo@gmail.com>
Acked-by: Angela Cristina <acristina@redaction-technique.org>