Fixed Linux Makefile error message

Makefile

@@ -37,7 +37,7 @@ endif
 ifneq ("$(wildcard $(BUILD_TOP)/Config.make)","")
   include $(BUILD_TOP)/Config.make
 else
-  $(error Cannot find $(BUILD_TOP)/Config.make.  Please see the README file for configuration instructions.)
+  $(error Cannot find $(BUILD_TOP)/Config.make.  Please see CNTK Wiki at https://github.com/Microsoft/cntk/wiki for configuration instructions.)
 endif
 
 ifndef BUILDTYPE