Update URL and name of coastline dataset

Author: rwogburn

doc/users/geography.rst

@@ -3,8 +3,8 @@
 Drawing a Map Background
 ========================
 
-Basemap includes the 
-`GSSH <http://www.soest.hawaii.edu/wessel/gshhs/gshhs.html>`_
+Basemap includes the GSSH
+`(now GSHHG <https://www.soest.hawaii.edu/pwessel/gshhg/>)`_
 coastline dataset, as well as datasets for rivers, state and
 country boundaries from 
 `GMT <http://gmt.soest.hawaii.edu>`_.