README.md in aixm-0.3.1 vs README.md in aixm-0.3.2

@@ -72,10 +72,11 @@
 
 ### Fundamentals
 * [Document](http://www.rubydoc.info/gems/aixm/AIXM/Document.html)
 * [XY (longitude and latitude)](http://www.rubydoc.info/gems/aixm/AIXM/XY.html)
 * [Z (height, elevation or altitude)](http://www.rubydoc.info/gems/aixm/AIXM/Z.html)
+* [D (distance or length)](http://www.rubydoc.info/gems/aixm/AIXM/D.html)
 * [F (frequency)](http://www.rubydoc.info/gems/aixm/AIXM/F.html)
 
 ### Features
 * [Organisation](http://www.rubydoc.info/gems/aixm/AIXM/Feature/Organisation.html)
 * [Unit](http://www.rubydoc.info/gems/aixm/AIXM/Feature/Unit.html)
@@ -86,9 +87,10 @@
   * [DME](http://www.rubydoc.info/gems/aixm/AIXM/Feature/DME.html)
   * [Marker](http://www.rubydoc.info/gems/aixm/AIXM/Feature/Marker.html)
   * [NDB](http://www.rubydoc.info/gems/aixm/AIXM/Feature/NDB.html)
   * [TACAN](http://www.rubydoc.info/gems/aixm/AIXM/Feature/TACAN.html)
   * [VOR](http://www.rubydoc.info/gems/aixm/AIXM/Feature/VOR.html)
+* [Obstacle and obstacle group](http://www.rubydoc.info/gems/aixm/AIXM/Feature/Obstacle.html)
 
 ### Components
 * [Service](http://www.rubydoc.info/gems/aixm/AIXM/Component/Service.html)
 * [Frequency](http://www.rubydoc.info/gems/aixm/AIXM/Component/Frequency.html)
 * [Geometry](http://www.rubydoc.info/gems/aixm/AIXM/Component/Geometry.html)