ref-manual: Added the buildhistory class.

(From yocto-docs rev: 8a04660072fdefe556d29ed010476512b899cbc7)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/ref-classes.xml

@@ -325,6 +325,19 @@
     </para>
 </section>
 
+<section id='ref-classes-buildhistory'>
+    <title><filename>buildhistory.bbclass</filename></title>
+
+    <para>
+        The Build History (<filename>buildhistory</filename>) class records a
+        history of build output metadata, which can be used to detect possible
+        regressions as well as used for analysis of the build output.
+        For more information on usinig Build History, see the
+        "<link linkend='maintaining-build-output-quality'>Maintaining Build Output Quality</link>"
+        section.
+    </para>
+</section>
+
 <section id='ref-classes-debian'>
     <title>Debian Renaming - <filename>debian.bbclass</filename></title>