Add example using since and until parameters.

Author: jterstriep

sensors/06-list-datasets-by-plot.md

@@ -6,7 +6,7 @@ from the workbench or Globus.
 
 ## Getting started
 
-After installing terrautils, you should be able to import the *prooduct* module.
+After installing terrautils, you should be able to import the *product* module.
 ```
 from terrautils.products import get_sensor_list, unique_sensor_names
 from terrautils.products import get_file_listing, extract_file_paths
@@ -20,17 +20,18 @@ The *key* is a unique access key for the Clowder api.
 ## Getting the sensor list
 The first thing to get is the sensor name. This can be retreived using the
 get\_sensor\_list function. This function returns the full record which may
-be useful in some cases but also includes sensor names that include a plot id
-number. The utility function unique_sensor_names accpets the sensor list and
-provides a list of names suitable for use in the get_file_listing function.
+be useful in some cases but primarily includes sensor names that include
+a plot id number. The utility function unique_sensor_names accpets the 
+sensor list and provides a list of names suitable for use in the 
+get_file_listing function.
 
 ```
 sensors = get_sensor_list(None, url, key)
 names = unique_sensor_names(sensors)
 ```
 
-Names will now contain a list of sensor names support by the Clowder geostreams
-API. The currently available sensors are:
+Names will now contain a list of sensor names available in the Clowder
+geostreams API. The currently available sensors are:
 
 * IR Surface Temperature
 * Thermal IR GeoTIFFs Datasets
@@ -61,6 +62,14 @@ datasets = get_file_listing(None, url, key, sensor, sitename)
 files = extract_file_paths(datasets)
 ```
 
+Datasets can be further filtered using the *since* and *until* parameters
+of get\_file\_listing with a date string.
+
+```
+dataset = get_file_listing(None, url, key, sensor, sitename, 
+        since='2016-06-01', until='2016-06-10')
+```
+
 
 # Alternative method
 The following method demonstrates the same approach using the Clowder API. This