Sphinx handling of 404 page is not that easy when using theme
customizations. Enabled the `sphinx-notfound-page` extension (maintained
by readthedocs) to fix its displaying.
Also adjusted Zephyr logo (was causing some Sphinx processing errors
when trying to scale it).
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
Add infrastructure for switching production documentation to use the
cleaner read_the_docs theme as noted in issue #6774. This change won't
affect the current "daily" or "release" builds but will change local
builds that previously also used the RTD theme, but now have the version
selection capability added.
This PR also adds the Zephyr logo and favicon to the RTD-themed docs,
and moves the top level images into an images/ folder.
Note that issue #9128 requires workaround.rst to force a reference to
files needed for the build but not directly referened in a .rst file.
(When #9128 is fixed, we can remove this workaround.rst.)
Once merged and tested, we'll tweak the conf.py to use the RTD theme
for all doc builds (e.g, when DOC_TAG=daily or release) in a subsequent
PR.
Signed-off-by: David B. Kinder <david.b.kinder@intel.com>