Documentation/process: Add Linux Kernel Contribution Maturity Model

Documentation/process: Add Linux Kernel Contribution Maturity Model

As a follow-up to a discussion at the 2021 Maintainer's Summit on the
topic of maintainer recruitment and retention, the TAB took on the
task of creating a document which to help companies and other
organizations to grow in their ability to engage with the Linux Kernel
development community, using the Maturity Model[2] framework.

The goal is to encourage, in a management-friendly way, companies to
allow their engineers to contribute with the upstream Linux Kernel
development community, so we can grow the "talent pipeline" for
contributors to become respected leaders, and eventually kernel
maintainers.

[1] https://lwn.net/Articles/870581/
[2] https://en.wikipedia.org/wiki/Maturity_model

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20230308190403.2157046-1-tytso@mit.edu
Signed-off-by: Jonathan Corbet <corbet@lwn.net>