Updates all `help()` output to use the phrase:
`For online docs please visit http://docs.micropython.org/`
Some ports previously used different wording, some pointed to the wrong
link. Also make all ports use `help.c` for consistency.
This work was funded through GitHub Sponsors.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This is to keep the top-level directory clean, to make it clear what is
core and what is a port, and to allow the repository to grow with new ports
in a sustainable way.
