documentation/poky-ref-manual: Section name change

I changed the "Reference: Images" section to "Images".  This old
name was a hold over from when the book had appendices that were
reference-like.  Along with changing the name I also fixed two
links to the section that were found in the variables chapter.

(From yocto-docs rev: e21a973cfe07d21acdfe02b49aa86c7672905968)

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

documentation/poky-ref-manual/ref-features.xml

@@ -112,7 +112,7 @@
     </section>
 
     <section id='ref-features-image'>
-        <title>Reference: Images</title>
+        <title>Images</title>
 
         <para>
             The contents of images generated by the OpenEmbedded build system can be controlled by the 

documentation/poky-ref-manual/ref-variables.xml

@@ -564,7 +564,7 @@
                     </literallayout> 
 
                  <para>There are other valid features too, see the
-                 <link linkend='ref-features-image'>Reference: Images</link>
+                 <link linkend='ref-features-image'>Images</link>
                  section for more details.</para>
             </glossdef>
         </glossentry>
@@ -784,7 +784,7 @@ FILESPATH = "${@base_set_filespath([ "${FILE_DIRNAME}/${PF}", \
                 Typically, you configure this variable in image recipes.
                 Note that you can add extra features to the image by using the
                 <filename><link linkend='var-EXTRA_IMAGE_FEATURES'>EXTRA_IMAGE_FEATURES</link></filename> variable.
-                See the "<link linkend="ref-features-image">Images</link>" chapter for the 
+                See the "<link linkend="ref-features-image">Images</link>" section for the 
                 list of features present in images built by the OpenEmbedded build system.</para>
             </glossdef>
         </glossentry>