This commit replaces the Zephyr logo for the HTML documentations with
the new registered trademark version.
Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
Adjust the Doxygen theme (based on doxygen-awesome) to match the Sphinx
theme. While not perfect, the experience should now be more consistent.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>