documentation: top-level manuals edited for new structure

I updated dev-manual.xml to include the new common tasks file
'dev-manual-common-tasks.xml' and updated poky-ref-manual.xml
to not have the file 'extended.xml'.  This reflects the new
chapter swap between the YP reference manual and the YP
development manual.

(From yocto-docs rev: 978e3be4f20b0a95cf124ce1a9136016a3e71da1)

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

documentation/dev-manual/dev-manual.xml

@@ -66,6 +66,8 @@
 
     <xi:include href="dev-manual-newbie.xml"/>
 
+    <xi:include href="dev-manual-common-tasks.xml"/>
+
     <xi:include href="dev-manual-model.xml"/>
 
     <xi:include href="dev-manual-bsp-appendix.xml"/>

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

@@ -90,8 +90,6 @@
 
     <xi:include href="usingpoky.xml"/>
 
-    <xi:include href="extendpoky.xml"/>
-
     <xi:include href="technical-details.xml"/>
 
     <xi:include href="../bsp-guide/bsp.xml"/>