added a color query example to doc
added a color query example to doc

albireox/marvin,bretthandrews/marvin,sdss/marvin,bretthandrews/marvin,sdss/marvin,bretthandrews/marvin,sdss/marvin,albireox/marvin,albireox/marvin,sdss/marvin,bretthandrews/marvin,albireox/marvin