Added gitignore and license information

.gitignore

@@ -0,0 +1,13 @@
+# G-Code
+*.g
+*.gco
+*.gcode
+*.nc
+
+# Exported files
+*.stl
+*.off
+*.amf
+*.dxf
+*.svg
+*.csg

README.md

@@ -1,3 +1,7 @@
 # pd-buddy-openscad
 
-OpenSCAD 3D models for use with PD Buddy devices
+OpenSCAD 3D models for use with PD Buddy devices
+
+## Licensing
+
+This work is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.