dev-manual, ref-manual: Changed section heading for multiconfig builds

Changed the section heading in the dev-manual for building images for
multiple targets useing multiple configurations.  This wording is
more accurate.  I updated the link from the BBMULTI_CONFIG variable
description as well.

(From yocto-docs rev: 3b2f95c3c54bed7ab8b4673ba7a254d31bea811b)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/dev-manual/dev-manual-common-tasks.xml

@@ -5321,8 +5321,8 @@
             </para>
         </section>
 
-        <section id='platdev-building-targets-with-multiple-configurations'>
-            <title>Building Targets with Multiple Configurations</title>
+        <section id='dev-building-images-for-multiple-targets-using-multiple-configurations'>
+            <title>Building Images for Multiple Targets Using Multiple Configurations</title>
 
             <para>
                 Bitbake also has functionality that allows you to build

documentation/ref-manual/ref-variables.xml

@@ -1336,7 +1336,7 @@
                     <filename>BBMULTICONFIG</filename> in an environment that
                     supports building targets with multiple configurations,
                     see the
-                    "<ulink url='&YOCTO_DOCS_DEV_URL;#platdev-building-targets-with-multiple-configurations'>Building Targets with Multiple Configurations</ulink>"
+                    "<ulink url='&YOCTO_DOCS_DEV_URL;#dev-building-images-for-multiple-targets-using-multiple-configurations'>Building Images for Multiple Targets Using Multiple Configurations</ulink>"
                     section in the Yocto Project Development Tasks Manual.
                 </para>
             </glossdef>