docs: conf.py: add CJK package needed by translations

In order to be able to output Asian symbols with XeLaTeX, we
need the xeCJK package, and a default font for CJK symbols.
Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/conf.py

@@ -277,6 +277,10 @@ latex_elements = {
         \\setromanfont{DejaVu Serif}
         \\setmonofont{DejaVu Sans Mono}
 
+	% This is needed for translations
+        \\usepackage{xeCJK}
+        \\setCJKmainfont{Noto Sans CJK SC}
+
      '''
 }