Update README.md

README.md

@@ -5,7 +5,16 @@ This script pulls 311 reports of vacant and abandoned buildings from the City of
 Source: https://data.cityofchicago.org/Service-Requests/311-Service-Requests-Vacant-and-Abandoned-Building/7nii-7srd
 Destination: http://www.google.com/fusiontables/DataSource?dsrcid=1614852 
 
+This import script has 2 modes: 
+
+- importing into Google Fusion Tables **deprecated**
+- exporting to a CSV file
+
+To use CSV mode, set `$dump_to_csv = true;` in `source/connectioninfo.php`
+
+In CSV mode, the script pulls down a CSV from the Socrata data portal and removes any duplicate rows for addresses that it has already seen.
+
 usage
-1. copy source/connectioninfo.php.example to source/connectioninfo.php
-2. fill in your Socrata and Google account info in source/connectioninfo.php
-2. $ php run_import.php
+1. `cp source/connectioninfo.php.example to source/connectioninfo.php`
+2. save your settings in source/connectioninfo.php
+3. `php run_import.php`