doc: remove breathe

Breathe is no longer used in Zephyr, mainly to its poor performance and
lack of proper maintainership. Therefore, do not recommend it in our
template application. Previous external C references do not work either,
so let's remove them. We may polish doxybridge/runner in the future and
make it a published extension on PyPI so that 3rd party repos like
applications can use it.

Signed-off-by: Gerard Marull-Paretas <gerard@teslabs.com>

Author: gmarull

doc/conf.py

@@ -14,7 +14,7 @@
 # -- General configuration ---------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration
 
-extensions = ['sphinx.ext.intersphinx', 'breathe']
+extensions = ['sphinx.ext.intersphinx']
 
 templates_path = ['_templates']
 exclude_patterns = ['_build_sphinx', 'Thumbs.db', '.DS_Store']
@@ -28,13 +28,3 @@
 # https://www.sphinx-doc.org/en/master/usage/extensions/intersphinx.html
 
 intersphinx_mapping = {'zephyr': ('https://docs.zephyrproject.org/latest/', None)}
-
-## -- Options for Breathe ----------------------------------------------------
-# https://breathe.readthedocs.io/en/latest/index.html
-#
-# WARNING: please, check breathe maintainership status before using this
-# extension in production!
-
-breathe_projects = {'example-application': '_build_doxygen/xml'}
-breathe_default_project = 'example-application'
-breathe_default_members = ('members', )

doc/drivers/blink.rst

@@ -7,8 +7,6 @@ This is a simple Sphinx documentation setup for ``example-application``.
    :maxdepth: 2
    :caption: Contents
 
-   drivers/index
-   lib/index
    zephyr
 
 Indices and tables

doc/drivers/index.rst

@@ -1,2 +1 @@
 Sphinx
-breathe

doc/index.rst

@@ -2,4 +2,4 @@ Zephyr
 ======
 
 You can reference Zephyr documentation items, like
-:external+zephyr:ref:`getting_started` or :external+zephyr:c:func:`k_sleep`.
+:external+zephyr:ref:`getting_started`.