Fixed links in README

README.md

 [kicad-library][] repository to ensure that you're using the latest schematic
 libraries.
 
+[KiCad]: http://kicad-pcb.org/
+[kicad-library]: https://github.com/KiCad/kicad-library/
+
 ## License
 
 PD Buddy Wye is Copyright (C) 2017 Clayton G. Hobbs, and made available under