Update freebsd-update major upgrade instructions to offer 'pkg upgrade' in addition to portmaster.

Differential Revision:	https://reviews.freebsd.org/D1288
Reviewed by:	bapt
Approved by:	bcr (mentor)
Sponsored by:	ScaleEngine Inc.

en_US.ISO8859-1/books/handbook/cutting-edge/chapter.xml

@@ -590,17 +590,31 @@ before running "/usr/sbin/freebsd-update install"</screen>
       </sect3>
 
       <sect3 xml:id="freebsdupdate-portsrebuild">
-	<title>Rebuilding Ports After a Major Version Upgrade</title>
+	<title>Upgrading Packages After a Major Version
+	  Upgrade</title>
 
 	<para>Generally, installed applications will continue to work
 	  without problems after minor version upgrades.  Major
 	  versions use different Application Binary Interfaces
 	  (<acronym>ABI</acronym>s), which will break most
 	  third-party applications.  After a major version upgrade,
-	  all installed packages and ports need to be upgraded using a
-	  utility such as <package>ports-mgmt/portmaster</package>.  A
-	  rebuild of all installed applications can be accomplished
-	  with this command:</para>
+	  all installed packages and ports need to be upgraded.
+	  Packages can be upgraded using <command>pkg
+	    upgrade</command>.  To upgrade installed ports, use a
+	  utility such as
+	  <package>ports-mgmt/portmaster</package>.</para>
+
+	<para>A forced upgrade of all installed packages with replace
+	  the packages with fresh versions from the repository even if
+	  the version number has not increased.  This is required
+	  because of the ABI version change when upgrading between
+	  major versions of &os;.  The forced upgrade can be
+	  accomplished by performing:</para>
+
+	<screen>&prompt.root; <userinput>pkg-static upgrade -f</userinput></screen>
+
+	<para>A rebuild of all installed applications can be
+	  accomplished with this command:</para>
 
 	<screen>&prompt.root; <userinput>portmaster -af</userinput></screen>