handbook: add documentation for layers

Collections and overlays are deprecated in favour of layers, a much cleaner and
non-intrusive way of extending Poky with custom recipes, classes and
configuration.

This patch updates the Extending Poky section of the handbook to show how to
use layers to tailor Poky while dropping  the existing section on using
collections.

Signed-off-by: Joshua Lock <josh@linux.intel.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/handbook/ref-bitbake.xml b/handbook/ref-bitbake.xml
index 8652424466..ddf3c760f2 100644
--- a/handbook/ref-bitbake.xml
+++ b/handbook/ref-bitbake.xml
@@ -81,9 +81,10 @@
             default this specifies the <filename class="directory">meta/packages/
             </filename> directory within Poky, but other directories such as
             <filename class="directory">meta-extras/</filename> can be included 
-            too. If multiple directories are specified a system referred to as 
-            <link linkend='usingpoky-changes-collections'>"collections"</link> is used to 
-            determine which files have priority.
+            too. Adding extra content to
+            <glossterm><link linkend='var-BBFILES'>BBFILES</link></glossterm> is best
+            acheived through the use of Bitbake
+            <link linkend='usingpoky-changes-layers'>"layers"</link>.
         </para>
 
         <para>