Update Download OSM Data XAPI Tool help text

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Update the tool help examples to use "highway=motorway", etc., rather than "way[highway=motorway]", as the latter can result in an empty .osm file being created.

If you enter way[highway=motorway], you get a "bad request" respons of the XAPI server, because the tool will also prepend the Download OSM type parameter, causing a double entry of this value (automatically by the tool and by you as the user).