docs: programming-language: add Rust programming language section

docs: programming-language: add Rust programming language section

Following the C text in the file, add a mention about the Rust
programming language, the currently supported compiler and
the edition used (similar to the "dialect" mention for C).

Similarly, add a mention about the unstable features used (similar
to the "extensions" mentions for C).

In addition, add some links to complement the information.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20230306191712.230658-2-ojeda@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>