Update gpcp.xml

Correct a typo.

Author: zjbdragon

input/gpcp.xml

@@ -530,7 +530,7 @@
     </sec:Roles>
 
 <!--   1.6 Package Usage -->
-<section title="Package Usage">
+	<section title="Package Usage">
       This section contains selections and assignments that are required when the listed Functional Packages are claimed by this PP. 
       <package-usage-list>
         <package-usage ref="X509">