リンク切れを修正 #1561

Author: faithandbrave

reference/memory/allocator.md

@@ -136,7 +136,7 @@ int main(int argc, char** argv) {
     - [Visual C++](/implementation.md#visual_cpp): 2012, 2013
 
 ## 参照
-- [A visitor’s guide to C++ allocators](https://rawgit.com/google/cxx-std-draft/allocator-paper/allocator_user_guide.html)
+- [A visitor’s guide to C++ allocators](https://htmlpreview.github.io/?https://github.com/google/cxx-std-draft/blob/allocator-paper/allocator_user_guide.html)
 - [LWG #2103 - `std::allocator_traits<std::allocator<T>>::propagate_on_container_move_assignment`](http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2103)
 - [N2669 Thread-Safety in the Standard Library (Rev 2)](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2669.htm)
 - [AllocatorAwareContainer: Introduction and pitfalls of `propagate_on_container_XXX` defaults](https://www.foonathan.net/2015/10/allocatorawarecontainer-propagation-pitfalls/)