documentation: dev-manual - Updated Enabling Your Layer section

This section was out of date.  I copied in the most recent version
of the bblayers.conf file, which sets LCONF_VERSION to "6" now.
Also, added the meta-yocto-bsp layer to the example.

Additionally, I inserted a Note explaining the consequences of
removing the meta-yocto layer.  The note references [YOCTO_#3176]
for more information.

(From yocto-docs rev: 532b72c5c18b2a9a61619164bae6216c91c2ecc9)

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

documentation/dev-manual/dev-manual-common-tasks.xml

@@ -213,13 +213,15 @@
                 <literallayout class='monospaced'>
      LCONF_VERSION = "6"
 
+     BBPATH = "${TOPDIR}"
      BBFILES ?= ""
-     BBLAYERS = " \
+
+     BBLAYERS ?= " \
        /path/to/poky/meta \
        /path/to/poky/meta-yocto \
        /path/to/poky/meta-yocto-bsp \
        /path/to/poky/meta-mylayer \
-       "
+       "                
                 </literallayout>
             </para>
 
@@ -230,6 +232,14 @@
                 During the processing of each <filename>conf/layer.conf</filename> file, BitBake adds the 
                 recipes, classes and configurations contained within the particular layer to the source
                 directory.
+                <note>
+                    Removing the <filename>meta-yocto</filename> layer exposes a bug for the 
+                    current release of the Yocto Project.
+                    If for some reason you do remove this layer from the 
+                    <filename>bblayers.conf</filename>, you must set the 
+                    <filename>LCONF_VERSION</filename> variable to "5".
+                    See <ulink url='https://bugzilla.yoctoproject.org/show_bug.cgi?id=3176'>[YOCTO_#3176]</ulink>
+                    for more information.</note>
             </para>
         </section>