Add FreeCAD link to README

Author: hsrai

README.md

@@ -1,6 +1,8 @@
 # BIM
 Working towards Digital Transformation in Civil Engineering, using  Open Standards
 
+[FreeCAD](FREECAD.md)
+
 ## Open Source Softwares On Which We Work
 * [FreeCAD](https://www.freecad.org)
 Role: Parametric 3D Modeling & BIM Authoring.