Add file location

Put this file at `/usr/share/X11/xkb/symbols/pc` to take effect.

Install/Templates/system/X11/xkb/symbols/pc

@@ -1,3 +1,4 @@
+// File must rely at /usr/share/X11/xkb/symbols/pc
 default  partial alphanumeric_keys modifier_keys
 xkb_symbols "pc105" {