Update README.md

Author: foreachthing

README.md

@@ -2,6 +2,7 @@
 Post processing for Slic3r to color the toolpaths to view in Craftware.
 
 * The option `verbose` in Slic3r _(Slic3r -> Print Settings -> Output options)_, needs to be set to true.
+  * In Post-Processing Scripts, add the full path to _this_ exe.
 * In Slic3r -> Printer -> Custom G-Code; add this:
   * Start G-Code: `; END Header`
   * End G-Code: `; END Footer`