docs(topojson-export): add topojson response documentation #650

Job	Run time
Build default builder image	2m 7s
Integration tests (maven, integrationtests.ConfigEnvironmentTest)	6m 21s
Integration tests (maven, integrationtests.ConfigFileTest)	5m 56s
Integration tests (maven, integrationtests.ConfigLookupTest)	6m 31s
Integration tests (maven, integrationtests.GeoToolsTest)	5m 26s
Integration tests (maven, integrationtests.GraphRepoTest)	8m 39s
Integration tests (jar, integrationtests.ConfigEnvironmentTest)	2m 52s
Integration tests (jar, integrationtests.ConfigFileTest)	2m 21s
Integration tests (jar, integrationtests.ConfigLookupTest)	2m 50s
Integration tests (jar, integrationtests.GeoToolsTest)	2m 12s
Integration tests (jar, integrationtests.GraphRepoTest)	3m 51s
Integration tests (war, integrationtests.ConfigEnvironmentTest)	3m 34s
Integration tests (war, integrationtests.ConfigFileTest)	2m 36s
Integration tests (war, integrationtests.ConfigLookupTest)	3m 31s
Integration tests (war, integrationtests.GeoToolsTest)	2m 58s
Integration tests (war, integrationtests.GraphRepoTest)	4m 49s
	1h 6m 34s

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