docs-rst: create a book for the development process

Now that the files at Documentation/development-process/
were converted to ReST, make create a book at Sphinx.

As we'll have other books related to the development process,
we'll add it as a sub-book.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/index.rst b/Documentation/index.rst
index 9fe5e0c..d9ccb94 100644
--- a/Documentation/index.rst
+++ b/Documentation/index.rst
@@ -12,6 +12,7 @@
    :maxdepth: 2
 
    kernel-documentation
+   development-process/index
    dev-tools/tools
    driver-api/index
    media/index