documentation: Moved devtool workflow to sdk manual

Fixes [YOCTO #11630]

The section on the devtool workflow in the dev-manual was 99%
identical to what was in the sdk-manual.  I have moved the
workflow procedure from the old "Model" chapter of the dev-manual
to be merged with what was in the sdk-manual.  In truth, the
only things added were a note about devtool not being exclusive
to SDK development.

The result of moving (deleting) this section was that the "model"
chapter of the dev-manual went away.  The devtool stuff, Quilt,
devshell, and python shell are all out now and there is no
chapter left.  So, mega-manual had to be adjusted to not pull that
chapter in when building the dev-manual.  I had to delete three
figures that were used in the flow.  The figures were already
replicated in the sdk-manual.  The figures were deleted from the
figures folder of both the dev-manual and the mega-manual.

I had to make sure all references to the old devtool stuf in the
YP doc set were adjusted.

(From yocto-docs rev: 5dbd643d31ab502df53a22229e457a03da7772b7)

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

documentation/sdk-manual/sdk-extensible.xml

@@ -235,6 +235,13 @@
             you build, test and package software within the extensible SDK, and
             optionally integrate it into an image built by the OpenEmbedded
             build system.
+            <note><title>Tip</title>
+                The use of <filename>devtool</filename> is not limited to
+                the extensible SDK.
+                You can use <filename>devtool</filename> to help you easily
+                develop any project whose build output must be part of an
+                image built using the OpenEmbedded build system.
+            </note>
         </para>
 
         <para>
@@ -244,6 +251,12 @@
             number of sub-commands for each function.
             You can run <filename>devtool --help</filename> to see all the
             commands.
+            <note>
+                See the
+                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-devtool-reference'><filename>devtool</filename>&nbsp;Quick Reference</ulink>"
+                in the Yocto Project Reference Manual for a
+                <filename>devtool</filename> quick reference.
+            </note>
         </para>
 
         <para>
@@ -1262,7 +1275,7 @@
         <title>Working With Recipes</title>
 
         <para>
-            When building a recipe with <filename>devtool build</filename> the
+            When building a recipe with <filename>devtool build</filename>, the
             typical build progression is as follows:
             <orderedlist>
                 <listitem><para>