Document <sync> behavior, PR 28757

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@277979 13f79535-47bb-0310-9956-ffa450edef68

docs/manual/CoreTasks/sync.html

@@ -15,6 +15,11 @@
 <p>Synchronize a target directory from the files defined in one or
 more filesets.</p>
 
+<p>Any file in the target directory that has not been matched by at
+least one of the nested filesets gets removed.  I.e. if you exclude a
+file in your sources and a file of that name is present in the target
+dir, it will get removed from the target.</p>
+
 <h3>Parameters</h3>
 <table border="1" cellpadding="2" cellspacing="0">
   <tr>