ref-manual: generalize definition of "container layer"

Given that there seems to be little value in being excruciatingly
pedantic about whether a container layer has a valid layer as a
top-level directory, expand the definition to allow either.

(From yocto-docs rev: 95e5df9a51a7cda6588af523a3a0d6752613f189)

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Reviewed-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 21 insertions, 4 deletions

diff --git a/documentation/ref-manual/terms.rst b/documentation/ref-manual/terms.rst
index eccae91a1c..89b140e3fe 100644
--- a/documentation/ref-manual/terms.rst
+++ b/documentation/ref-manual/terms.rst
@@ -134,10 +134,27 @@ universal, the list includes them just in case:
       the Texas Instruments ARM Cortex-A8 development board).
 
    :term:`Container Layer`
-      Layers that hold other layers. An example of a container layer is
-      OpenEmbedded's `meta-openembedded
-      <https://github.com/openembedded/meta-openembedded>`_ layer. The
-      ``meta-openembedded`` layer contains many ``meta-*`` layers.
+      A flexible definition that typically refers to a single Git checkout
+      which contains multiple (and typically related) sub-layers which can
+      be included independently in your project's ``bblayers.conf`` file.
+
+      In some cases, such as with OpenEmbedded's
+      `meta-openembedded <https://github.com/openembedded/meta-openembedded>`_
+      layer, the top level ``meta-openembedded/`` directory is not itself an actual layer,
+      so you would never explicitly include it in a ``bblayers.conf`` file;
+      rather, you would include any number of its layer subdirectories, such as
+      `meta-openembedded/meta-oe <https://github.com/openembedded/meta-openembedded/tree/master/meta-oe>`_,
+      `meta-openembedded/meta-python <https://github.com/openembedded/meta-openembedded/tree/master/meta-python>`_
+      and so on.
+
+      On the other hand, some container layers (such as
+      `meta-security <https://git.yoctoproject.org/cgit/cgit.cgi/meta-security>`_)
+      have a top-level directory that is itself an actual layer, as well as
+      a variety of sub-layers, both of which could be included in your
+      ``bblayers.conf`` file.
+
+      In either case, the phrase "container layer" is simply used to describe
+      a directory structure which contains multiple valid OpenEmbedded layers.
 
    :term:`Cross-Development Toolchain`
       In general, a cross-development toolchain is a collection of software