Add OpenSCAD to gitignore

.gitignore

@@ -6,6 +6,10 @@ Session.vim
 .netrwhist
 *~
 
+# ---> OpenSCAD
+*.stl
+*.dxf
+
 # ---> KiCAD
 # For PCBs designed using KiCAD: http://www.kicad-pcb.org/