Fixed typo in changes.xml file.

src/changes/changes.xml

@@ -48,26 +48,26 @@
       <action dev="evan" type="fix" issue="636">
         Fix UT1 and Earth rotation during a leap second. Was off by 1 second.
       </action>
-      <action def="luc" type="fix" issue="635">
+      <action dev="luc" type="fix" issue="635">
         Fixed inconsistency in constant thrust maneuver acceleration.
       </action>
-      <action def="evan" type="add" >
+      <action dev="evan" type="add" >
         Added an annotation and a compiler plugin that generates a warning
         when default context is used without being explicitly annotated.
       </action>
-      <action def="luc" type="fix" issue="632" due-to="Evan Ward">
+      <action dev="luc" type="fix" issue="632" due-to="Evan Ward">
         Fixed projection to ellipsoid at pole.
       </action>
       <action dev="evan,luc,yannick" type="add" issue="607">
         Add DataContext, a way to load separate sets of EOP, leap seconds, etc.
       </action>
-      <action def="luc" type="fix" issue="630">
+      <action dev="luc" type="fix" issue="630">
         Improve performance of UnixCompressFilter.
       </action>
-      <action def="luc" type="fix" issue="631">
+      <action dev="luc" type="fix" issue="631">
         Improve performance of HatanakaCompressFilter.
       </action>
-      <action def="evan" type="fix" issue="629">
+      <action dev="evan" type="fix" issue="629">
         Improve performance of ZipJarCrawler.
       </action>
       <action dev="bryan" type="add" issue="625">