minor doc improvements

[[Imported from SVN: r6682]]

dune/common/fvector.hh

@@ -126,10 +126,10 @@ namespace Dune {
     {}
 
     /**
-     * \brief Constructor making vector with identical coordinates
+     * \brief Copy constructor from a second vector of possibly different type
      *
-     * If the DenseVector type of the this constructors argument
-     * is impemented by a FieldVector, it is statically checked
+     * If the DenseVector type of the this constructor's argument
+     * is implemented by a FieldVector, it is statically checked
      * if it has the correct size. If this is not the case
      * the constructor is removed from the overload set using SFINAE.
      *