[docs] [PATCH v2] ref-manual: add "KERNEL_IMAGE_STRIP_EXTRA_SECTIONS" to variables

["Robert P. J. Day" <rpjday@crashcourse.ca>]

Add this variable to the variables glossary, and add links to it and
back to the do_strip() task for completeness.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>

---

diff --git a/documentation/ref-manual/tasks.rst b/documentation/ref-manual/tasks.rst
index e1db2d5ed..f328edd9b 100644
--- a/documentation/ref-manual/tasks.rst
+++ b/documentation/ref-manual/tasks.rst
@@ -848,11 +848,19 @@ the kernel build produces a warning to that effect.
 ``do_strip``
 ------------

-If ``KERNEL_IMAGE_STRIP_EXTRA_SECTIONS`` is defined, this task strips
+If :term:`KERNEL_IMAGE_STRIP_EXTRA_SECTIONS` is defined, this task strips
 the sections named in that variable from ``vmlinux``. This stripping is
 typically used to remove nonessential sections such as ``.comment``
 sections from a size-sensitive configuration.

+Common sections to strip:
+
+-  ``.comment``: Holds compiler version strings and information
+
+-  ``.note.*``: Extra notes often left by the compiler
+
+-  ``.debug``: Debugging information
+
 .. _ref-tasks-validate_branches:

 ``do_validate_branches``
diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index c92b195ff..cd5979a84 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -5623,6 +5623,13 @@ system and gives an overview of their function and contents.

       See :term:`KERNEL_ARTIFACT_NAME` for additional information.

+   :term:`KERNEL_IMAGE_STRIP_EXTRA_SECTIONS`
+      If this variable is set, it should contain the sections to be
+      stripped from the ``vmlinux`` image by the kernel-related
+      :ref:`ref-tasks-strip` task. As a simple example::
+
+         KERNEL_IMAGE_STRIP_EXTRA_SECTIONS = ".comment .note.* .debug"
+
    :term:`KERNEL_IMAGETYPE`
       The type of kernel to build for a device, usually set by the machine
       configuration files and defaults to "zImage". This variable is used