improve documentation of dense matrix vector classes

fix typo

[[Imported from SVN: r6136]]

dune/common/ftraits.hh

@@ -13,7 +13,7 @@ namespace Dune {
      \brief Type Traits to retrieve the field and the real type of classes
 
      Type Traits to retrieve the field and the real type of classes
-     e.g. that of FIeldVector or FieldMatrix
+     e.g. that of FieldVector or FieldMatrix
    */
   template<class T>
   struct FieldTraits