Fix broken link on README (#608)
Fix broken link on README (#608)

The developer docs are now more about how to develop higlass than how to use the API, so this seems right.
hms-dbmi/4DN_matrix-viewer,hms-dbmi/4DN_matrix-viewer,hms-dbmi/higlass,hms-dbmi/4DN_matrix-viewer,hms-dbmi/higlass,hms-dbmi/higlass,hms-dbmi/higlass