fixed comment and doc on L2

modules/features2d/doc/common_interfaces_of_descriptor_matchers.rst

@@ -290,7 +290,7 @@ For efficiency, ``BruteForceMatcher`` is used as a template parameterized with t
     template<> struct Accumulator<short>  { typedef int Type; };
 
     /*
-     * Squared Euclidean distance functor
+     * Euclidean distance functor
      */
     template<class T>
     struct L2

modules/features2d/include/opencv2/features2d/features2d.hpp

@@ -2084,7 +2084,7 @@ template<> struct Accumulator<char>   { typedef float Type; };
 template<> struct Accumulator<short>  { typedef float Type; };
 
 /*
- * Squared Euclidean distance functor
+ * Euclidean distance functor
  */
 template<class T>
 struct CV_EXPORTS L2