Skill code refers to incorrect readme file.  README.txt rather than README.md

The Skill file "GDS3D/skill/icdGDS3D.il"  Looks for a file called "README.txt". This should be "README.md"
I edited the skill code to point at the correct file, and then it worked fine.

Before I fixed the problem, I got the following error message in the CIW when I selected Layout->GDS3D:

icdWriteGDS3D()
Error: could not copy GDS3D readme to ~/GDS3D/
