sphinx.rst: Allow Sphinx version 1.6 at the docs

Now that the PDF building issues with Sphinx 1.6 got fixed,
update the documentation and scripts accordingly.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/doc-guide/sphinx.rst

@@ -80,9 +80,7 @@ output.
 PDF and LaTeX builds
 --------------------
 
-Such builds are currently supported only with Sphinx versions 1.4 and 1.5.
-
-Currently, it is not possible to do pdf builds with Sphinx version 1.6.
+Such builds are currently supported only with Sphinx versions 1.4 and upper.
 
 For PDF and LaTeX output, you'll also need ``XeLaTeX`` version 3.14159265.