ref-manual, adt-manual: Minor edits from review.

Fixed some wordings in the ADT manual to remove "Intel-based"
so as not to be biased.

Added "x86" to qualify the types of systems in the toolchain
examples.

Added minor wording to the IMAGE_TYPES variable.

Changed some wording for the IPK_FEED_URIS varilable.

(From yocto-docs rev: 1fa7e0000591bec7e3d0b682df02b95dbee3d4f1)

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

documentation/ref-manual/ref-variables.xml

@@ -1935,7 +1935,8 @@ Core layer for images cannot be removed
         <glossentry id='var-IMAGE_TYPES'><glossterm>IMAGE_TYPES</glossterm>
             <glossdef>
                 <para>
-                    Specifies the complete list of supported image types:
+                    Specifies the complete list of supported image types
+                    by default:
                     <literallayout class='monospaced'>
      jffs2
      sum.jffs2
@@ -2168,12 +2169,13 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
         <glossentry id='var-IPK_FEED_URIS'><glossterm>IPK_FEED_URIS</glossterm>
             <glossdef>
                 <para>
-                    Helps users set up an additional package feed area on
-                    a server for packages you might want to install on a
-                    target that is running an image.
+                    When the IPK backend is in use and package management
+                    is enabled on the target, you can use this variable to
+                    set up <filename>opkg</filename> in the target image
+                    to point to package feeds on a nominated server.
                     Once the feed is established, you can perform
                     installations or upgrades using the package manager
-                    at runtime (e.g. <filename>opkg</filename>).
+                    at runtime.
                 </para>
             </glossdef>
         </glossentry>