PEP 418: Add Boost.Chrono library in links

pep-0418.txt

@@ -916,6 +916,24 @@ Libraries exposing monotonic clocks:
 * `libpthread
   <http://code.google.com/p/libpthread/>`_: POSIX thread library for Windows
   (`clock.c <http://code.google.com/p/libpthread/source/browse/src/clock.c>`_)
+* `Boost.Chrono
+  <http://www.boost.org/doc/libs/1_49_0/doc/html/chrono.html>`_ uses:
+
+  * system_clock:
+
+    * mac = gettimeofday()
+    * posix = clock_gettime(CLOCK_REALTIME)
+    * win = GetSystemTimeAsFileTime()
+
+  * steady_clock:
+
+    * mac = mach_absolute_time()
+    * posix = clock_gettime(CLOCK_MONOTONIC)
+    * win = QueryPerformanceCounter()
+
+  * high_resolution_clock:
+
+    * steady_clock, if available system_clock, otherwise
 
 Time: