[#1946] T.65 Fix two typos (#1956)

Fixes #1946:
 - copy_trait type argument needs to be a container element type.
   Use Value_type<Iter> like in other examples.

 - Fix name typo in the definition of copy_helper.

CppCoreGuidelines.md

@@ -18248,7 +18248,7 @@ This is a simplified version of `std::copy` (ignoring the possibility of non-con
     template<class Iter>
     Out copy(Iter first, Iter last, Iter out)
     {
-        return copy_helper(first, last, out, typename copy_trait<Iter>::tag{})
+        return copy_helper(first, last, out, typename copy_trait<Value_type<Iter>>::tag{})
     }
 
     void use(vector<int>& vi, vector<int>& vi2, vector<string>& vs, vector<string>& vs2)
@@ -18264,7 +18264,7 @@ This is a general and powerful technique for compile-time algorithm selection.
 When `concept`s become widely available such alternatives can be distinguished directly:
 
     template<class Iter>
-        requires Pod<Value_type<iter>>
+        requires Pod<Value_type<Iter>>
     Out copy_helper(In, first, In last, Out out)
     {
         // use memmove