doc: fix cut&paste error

ChangeLog

@@ -4,14 +4,14 @@ Version 8.1.2 [devel] 2013-11-28
   Thanks to Pavel Levshin for his work in this regard.
 - support for jemalloc added via --enable-jemalloc
   Thanks to Pavel Levshin for suggesting jemalloc
+  Note that build system is experimental at this stage.
 - queue defaults have changed
   * high water mark is now dynamically 90% of queue size
   * low water makr is now dynamically 70% of queue size
   * queue.discardMark is now dynamically 98% of queue size
   * queue.workerThreadMinimumMessage set to queue.size / num workers
   For queues with very low queue.maxSize (< 100), "emergency" defaults
   will be used.
-  Note that build system is experiemental at this stage.
 - bugfix: disk queues created files in wrong working directory
   if the $WorkDirectory was changed multiple times, all queues only
   used the last value set.