Fix some markup errors

git-svn-id: https://svn.apache.org/repos/asf/maven/maven-1/plugins/trunk@329999 13f79535-47bb-0310-9956-ffa450edef68

pom/xdocs/validation.xml

@@ -37,7 +37,7 @@
         The validation routine works differently for stand-alone
         poms and poms that extend other ones (child poms).
         The following table shows which
-        top-level elements (<emph>i.e.</emph>, elements just below the
+        top-level elements (<em>i.e.</em>, elements just below the
         <code>&lt;project&gt;</code> root) are required in each case.
       </p>
       <table>