Update README.

Add hint for ISO 6709 string formatting.

Author: jenetics

README.md

@@ -4,7 +4,7 @@
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-**JPX** is a Java library for creating, reading and writing [GPS](https://en.wikipedia.org/wiki/Global_Positioning_System) data in [GPX](https://en.wikipedia.org/wiki/GPS_Exchange_Format) format. It is a *full* implementation of version [1.1](http://www.topografix.com/GPX/1/1/) and version [1.0](http://www.topografix.com/gpx_manual.asp) of the GPX format. The data classes are completely immutable and allows a functional programming style. They  are working also nicely with the Java 8 [Stream](http://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html) API.
+**JPX** is a Java library for creating, reading and writing [GPS](https://en.wikipedia.org/wiki/Global_Positioning_System) data in [GPX](https://en.wikipedia.org/wiki/GPS_Exchange_Format) format. It is a *full* implementation of version [1.1](http://www.topografix.com/GPX/1/1/) and version [1.0](http://www.topografix.com/gpx_manual.asp) of the GPX format. The data classes are completely immutable and allows a functional programming style. They  are working also nicely with the Java 8 [Stream](http://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html) API. It is also possible to convert the location information into strings which are compatible to the [ISO 6709](http://en.wikipedia.org/wiki/ISO_6709) standard.
 
 Beside the basic functionality of reading and writing GPX files, the library also allows to manipulate the read GPX object in a functional way.