ref-manual, dev-manual: Updates to support recipe-specific sysroots

Changes covered several areas.  Version 2.3 of the YP now supports
recipe-specific sysroots and is not limited to machine-specific
as was prior releases.  Manual changes were as follows:

dev-manual: "Sharing Files Between Recipes" - Wordings were changed
to support the new functionality.

ref-manual: do_prepare_recipe_sysroot task added to the list of
tasks described in "Configuration and Compilation".

ref-manual: Extensive re-write of the "staging.bbclass" section.

ref-manual: Added a section to the build structure for
build/tmp/work/tunearch/recipename/version/.  This section breaks
down the recipe-specific subdirectories used to create (stage)
the sysroot.

ref-manual: New section (entry) for the do_prepare_recipe_sysroot
task in the task chapter.

ref-manual: Added a variable glossary description for the
SSTATE_SCAN_FILES variable.

In addition to these changes, I sprinkled in a liberal amount
of cross-referencing for the readers pleasure.

(From yocto-docs rev: 3a8ca96861f4c5d3badb91d0cdc5a3df513d4e59)

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

documentation/ref-manual/ref-tasks.xml

@@ -490,6 +490,18 @@
         </para>
     </section>
 
+    <section id='ref-tasks-prepare_recipe_sysroot'>
+        <title><filename>do_prepare_recipe_sysroot</filename></title>
+
+        <para>
+            Installs the files into the individual recipe work directories
+            (i.e. WORKDIR).
+            See the
+            "<link linkend='ref-classes-staging'><filename>staging</filename></link>"
+            class for more information.
+        </para>
+    </section>
+
     <section id='ref-tasks-rm_work'>
         <title><filename>do_rm_work</filename></title>