Fix capitalization of KiCad

According to their website, the correct capitalization is KiCad, not KiCAD.

KiCad.gitignore

@@ -0,0 +1,13 @@
+# For PCBs designed using KiCad: http://www.kicad-pcb.org/
+
+# Temporary files
+*.000
+*.bak
+*.bck
+*.kicad_pcb-bak
+
+# Netlist files (exported from Eeschema)
+*.net
+
+# Autorouter files (exported from Pcbnew)
+.dsn