STYLE: fix typo

Alex

Source/cmTarget.cxx

@@ -91,7 +91,7 @@ void cmTarget::DefineProperties(cmake *cm)
   cm->DefineProperty
     ("EchoString", cmProperty::TARGET,
      "A message to be displayed when the target is built.",
-     "A message to display on some generaters (such as makefiles) when "
+     "A message to display on some generators (such as makefiles) when "
      "the target is built.");
 
   cm->DefineProperty