Update README to accurately reflect updating process

Author: joferkington

utils/README

@@ -1,3 +1,22 @@
+The border/coastline data used by basemap can be updated it two ways:
+
+A) Download the GSHHS shapefiles and use them
+B) Use GMT if you already have it installed, and avoid the download.
+
+The preferred method is to use the GSHHS shapefiles.
+
+Option A - GSHHS Shapefiles
+---------------------------
+
+1) Download the shapefile formatted versions of GSHHS and extract them in the
+   "utils" directory. The data is available at: 
+   https://www.soest.hawaii.edu/pwessel/gshhg/
+   (Last updated with: ftp://ftp.soest.hawaii.edu/gshhg/gshhg-shp-2.3.5-1.zip)
+2) Run readboundaries_shp.py.
+
+Option B - Generic Mapping Tools
+--------------------------------
+
 1) Install GMT. Note that you may need to install a separate gmt-suplemental
    package to get "gmt gshhg" on some systems.  
 2) Download gshhg native binary-formatted data from 
@@ -6,4 +25,3 @@
 3) run dumpbounds.sh to create states, countries, rivers text files.
 4) run readboundaries.py to process into binary files, with metadata in
    separate text files.
-5) run plotgrdlandmask.py to verify results.