Remove M48 credits also

Marlin/Marlin_main.cpp

@@ -2414,10 +2414,8 @@ inline void gcode_M42() {
       }
     }
 
-    if (verbose_level > 0)   {
-      SERIAL_PROTOCOLPGM("M48 Z-Probe Repeatability test.   Version 2.00\n");
-      SERIAL_PROTOCOLPGM("Full support at: http://3dprintboard.com/forum.php\n");
-    }
+    if (verbose_level > 0)
+      SERIAL_PROTOCOLPGM("M48 Z-Probe Repeatability test\n");
 
     if (code_seen('n')) {
       n_samples = code_value();