This will help us review the pages as we add typing to the documentation. Then they will be hidden again.
This commit can be cherry-picked later on if we ever enable NXT and EV3 content again.
The doc/api is a legacy name, which is confusing in the current use, since all build targets are now APIs.
Today we have:
doc/common: Common configuration and settings between all targets.
doc/main: Main Pybricks documentation at docs.pybricks.com.
doc/ide: Documentation shipped with the Pybricks Code IDE.