Implemented proposed resolution for LWG 3120

doc/container.qbk

@@ -1257,6 +1257,10 @@ use [*Boost.Container]? There are several reasons for that:
      found by Arthur O'Dowyer in his blog post
      [@https://quuxplusone.github.io/blog/2018/06/05/libcpp-memory-resource/ <memory_resource> for libc++]
 
+* Implemented proposed resolution for 
+  [@https://cplusplus.github.io/LWG/issue3120 ['"LWG 3120 Unclear behavior of monotonic_buffer_resource::release()"]].
+  After `release()` the original buffer is recovered for the next allocation.
+
 [endsect]
 
 [section:release_notes_boost_1_67_00 Boost 1.67 Release]