Add a couple of paragraphs to the "patch formatting" section on how patches
should be described.  This text is shamelessly cribbed from suggestions
posted by Rusty Russell.
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

This is an extended document intended to help interested developers, their
managers, and their employers work with the kernel development process.

This work was supported by the Linux Foundation.
Signed-off-by: NJonathan Corbet <corbet@lwn.net>