Use MICROPY_PY_BUILTINS_HELP_TEXT

[dlech]

It looks like PYBRICKS_OPT_RAW_REPL is disabled on most hubs, so that is why it doesn't work. I guess we should replace the default help with our own by setting MICROPY_PY_BUILTINS_HELP_TEXT.

Originally posted by @dlech in #2542 (reply in thread)

[dlech]

There are some things in the default help that aren't enabled, like the raw repl and it would be nice if it say "Pybricks MicroPython" instead of just "Python" and linked to our website (maybe the project page?).