[yocto] building the examples from "meta-demo"

[David Smoot]

Greetings.  I am trying to learn the Yocto build system and I think I
am missing one key step.  I have successfully built and tested several
of the built in images ("core-image-basic", "core-image-base", etc)
for my routerstation pro.  I now want to understand how to build my
own customized images with other people's recipes and my own custom
recipes.  I want to try the upnp demos from
http://git.yoctoproject.org/cgit/cgit.cgi/meta-demo/.

>From inside my poky folder, I did a "git clone
git://git.yoctoproject.org/meta-demo" so that I have the meta-demo
folder at the same level as the the other meta-* folders.
Outside my poky tree I did the "source poky/oe-init-build-env my-build-folder"
I edited conf/local.conf to set my parallel build options, my MACHINE
to routerstationpro, and my download directory variable.
I then typed "bitbake -k demo-image-mediatomb" but I got an error
message that "ERROR: Nothing PROVIDES 'demo-image-mediatomb'"

Obviously I have missed a step to tell poky how to find that image but
so far I have not been able to google the answer to my mistake.

Thanks in advance for any answers and thanks for such a cool tool.

David Smoot