ref-manual: Added the ownmirrors class and the SOURCE_MIRROR_URL variable.

(From yocto-docs rev: 32c1d7aeecb6face0030def431b10277974f30d5)

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

@@ -1243,6 +1243,32 @@
     </para>
 </section>
 
+<section id='ref-classes-ownmirrors'>
+    <title><filename>ownmirrors.bbclass</filename></title>
+
+    <para>
+        The own mirrors (<filename>ownmirrors</filename>) class makes it
+        easier to set up your own
+        <link linkend='var-PREMIRRORS'><filename>PREMIRRORS</filename></link>
+        from which to first fetch source before attempting to fetch it from the
+        upstream specified in
+        <link linkend='var-SRC_URI'><filename>SRC_URI</filename></link>
+        within each recipe.
+    </para>
+
+    <para>
+        To use this class, inherit it globally and specify
+        <link linkend='var-SOURCE_MIRROR_URL'><filename>SOURCE_MIRROR_URL</filename></link>.
+        Here is an example:
+        <literallayout class='monospaced'>
+     INHERIT += "own-mirrors"
+     SOURCE_MIRROR_URL = "http://example.com/my-source-mirror"
+        </literallayout>
+        You can specify only a single URL in
+        <filename>SOURCE_MIRROR_URL</filename>.
+    </para>
+</section>
+
 <section id='ref-classes-pkgconfig'>
     <title>Pkg-config - <filename>pkgconfig.bbclass</filename></title>