Added detail about the output of this attribute

Author: dlieou

HISTORY.rst

@@ -15,8 +15,10 @@ History
 * Python 3.3 and 3.4 are no longer supported.
 * Updated documentation of anonymizer attributes - ``is_anonymous_vpn`` and
   ``is_hosting_provider`` - to be more descriptive.
-* Added support for ``user_count`` trait for the GeoIP2 Precision webservice.
-* Added ``static_ip_score`` property to ``geoip2.record.Traits`` for GeoIP2 Precision Insights.
+* Added support for the ``user_count`` trait for the GeoIP2 Precision webservice.
+* Added the ``static_ip_score`` attribute to ``geoip2.record.Traits`` for 
+  GeoIP2 Precision Insights. This is a float which indicates how static or dynamic 
+  an IP address is.
 
 2.9.0 (2018-05-25)
 ++++++++++++++++++