typo

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@507833 13f79535-47bb-0310-9956-ffa450edef68

docs/manual/CoreTasks/parallel.html

@@ -90,7 +90,7 @@
 
 <p>Parallel tasks have a number of uses in an Ant build file including:</p>
 <ul>
-<li>Taking advantage of available processing resources to excute external
+<li>Taking advantage of available processing resources to execute external
  programs simultaneously.</li>
 <li>Testing servers, where the server can be run in one thread and the test
 harness is run in another thread.</li>