Documentation (#1086)

Add documentation for #1071.

include/gsl/pointers

@@ -68,8 +68,9 @@ using std::unique_ptr;
 //
 // owner
 //
-// owner<T> is designed as a bridge for code that must deal directly with owning pointers for some
-// reason
+// `gsl::owner<T>` is designed as a safety mechanism for code that must deal directly with raw pointers that own memory.
+// Ideally such code should be restricted to the implementation of low-level abstractions. `gsl::owner` can also be used
+// as a stepping point in converting legacy code to use more modern RAII constructs, such as smart pointers.
 //
 // T must be a pointer type
 // - disallow construction from any type other than pointer type