Fix typo.

Author: Gary Gregory

src/changes/changes.xml

@@ -176,7 +176,7 @@ The <action> type attribute can be add,update,fix,remove.
         Make ObservableInputStream.getObservers() public.
       </action>
       <action  issue="IO-706" dev="ggregory" type="add" due-to="Gary Gregory">
-        Add TimetampedObserver.
+        Add TimestampedObserver.
       </action>
       <action dev="ggregory" type="add" due-to="Gary Gregory">
         Add and use IOUtils.byteArray(*).