improve mapcss javadoc

git-svn-id: https://josm.openstreetmap.de/svn/trunk@7530 0c6e7542-c601-0410-84e7-c038aed88b3b
applied #10503 - Note download code (patch by ToeBee)


git-svn-id: https://josm.openstreetmap.de/svn/trunk@7531 0c6e7542-c601-0410-84e7-c038aed88b3b