update README w.r.t. TimeSpan support

Author: kevin-montrose

README.md

@@ -92,6 +92,8 @@ The following types (and any user defined types composed of them) are supported:
  - Floating point numbers (float, double, and decimal)
  - DateTimes & DateTimeOffsets
  * See Configuration for further details
+ - TimeSpans
+ * See Configuration for further details
  - Nullable types
  - Enumerations
  * Including \[Flags\]
@@ -107,11 +109,19 @@ declaration order).  The [`DataMemberAttribute.Name` property](http://msdn.micro
 
 Jil's `JSON.Serialize` and `JSON.Deserialize` methods take an optional `Options` parameter which controls:
 
- - The format of DateTimes & DateTimeOffsets, one of
- * NewtonsoftStyleMillisecondsSinceUnixEpoch, a string, ie. "\/Date(##...##)\/"
- * MillisecondsSinceUnixEpoch, a number, which can be passed directly to [JavaScript's Date() constructor](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date)
- * SecondsSinceUnixEpoch, a number, commonly refered to as [unix time](http://en.wikipedia.org/wiki/Unix_time)
- * ISO8601, a string, ie. "2011-07-14T19:43:37Z"
+ - The format of DateTimes, DateTimeOffsets, and TimeSpans; one of
+ * NewtonsoftStyleMillisecondsSinceUnixEpoch, a string
+   - "\/Date(##...##)\/" for DateTimes
+   - "1.23:45:56.78" for TimeSpans
+ * MillisecondsSinceUnixEpoch, a number
+   - for DateTimes it can be passed directly to [JavaScript's Date() constructor](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date)
+   - for TimeSpans it's simply [TimeSpan.TotalMilliseconds](http://msdn.microsoft.com/en-us/library/system.timespan.totalmilliseconds%28v=vs.110%29.aspx)
+ * SecondsSinceUnixEpoch, a number
+   - for DateTimes this is commonly refered to as [unix time](http://en.wikipedia.org/wiki/Unix_time)
+   - for TimeSpans it's simply [TimeSpan.TotalSeconds](http://msdn.microsoft.com/en-us/library/system.timespan.totalseconds%28v=vs.110%29.aspx)
+ * ISO8601, a string
+   - for DateTimes, ie. "2011-07-14T19:43:37Z"
+   - for TimeSpans, ie. "P40DT11H10M9.4S" 
  - Whether or not to exclude null values when serializing dictionaries, and object members
  - Whether or not to "pretty print" while serializing, which adds extra linebreaks and whitespace for presentation's sake
  - Whether or not the serialized JSON will be used as JSONP (which requires slightly more work be done w.r.t. escaping)