Document wxVector<T>::swap().

Closes #12253.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65041 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/vector.h

@@ -235,6 +235,17 @@ public:
         Returns the size of the vector.
     */
     size_type size() const;
+
+    /**
+        Efficiently exchanges contents of this vector with another one.
+
+        After the execution of this function the contents of this vector is
+        equal to the original contents of @a v and the contents of @a v becomes
+        the original contents of this vector without copying the data.
+
+        @since 2.9.1
+     */
+    void swap(wxVector& v);
 };