Enhanced this description by indicating the class that it is set in
and by including a pointer back into the sdk-manual where filters
are described for extending the extensible SDK.
(From yocto-docs rev: 355b05366aadc337ec3337c0a3c918a23027923b)
Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>