Updates all README.md and docs, and manifests to `require("mip")`.
Also extend and improve the documentation on freezing and packaging.
This work was funded through GitHub Sponsors.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This commit adds many new sections to the existing "Developing and building
MicroPython" chapter to make it all about the internals of MicroPython.
This work was done as part of Google's Season of Docs 2020.