README.md in rgeo-2.4.0 vs README.md in rgeo-3.0.0.pre.rc.1

@@ -127,9 +127,10 @@
 - [An introduction to Spatial Programming With RGeo](https://github.com/rgeo/rgeo/blob/master/doc/An-Introduction-to-Spatial-Programming-With-RGeo.md)
 - [Enable GEOS and Proj4 on Heroku](https://github.com/rgeo/rgeo/blob/master/doc/Enable-GEOS-and-Proj4-on-Heroku.md)
 - [Installing GEOS](https://github.com/rgeo/rgeo/blob/master/doc/Installing-GEOS.md)
 - [Factory Compatibility](https://github.com/rgeo/rgeo/blob/master/doc/Factory-Compatibility.md)
 - [Which factory should I use?](https://github.com/rgeo/rgeo/blob/master/doc/Which-factory-should-I-use.md)
+- [Geometry validity handling](https://github.com/rgeo/rgeo/blob/master/doc/Geometry-Validity.md)
 - [Examples](https://github.com/rgeo/rgeo/blob/master/doc/Examples.md)
 - [Who uses `rgeo`?](https://github.com/rgeo/rgeo/blob/master/doc/Gallery.md)
 
 You can see an exhaustive and up to date list at https://rubydoc.info/gems/rgeo/index.
 ### Acknowledgments