docs-rst: doc-guide: split the kernel-documentation.rst contents

Having the kernel-documentation at the topmost level doesn't
allow generating a separate PDF file for it. Also, makes harder
to add extra contents. So, place it on a sub-dir.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/doc-guide/conf.py

@@ -0,0 +1,10 @@
+# -*- coding: utf-8; mode: python -*-
+
+project = 'Linux Kernel Documentation Guide'
+
+tags.add("subproject")
+
+latex_documents = [
+    ('index', 'kernel-doc-guide.tex', 'Linux Kernel Documentation Guide',
+     'The kernel development community', 'manual'),
+]