docs/ci: clean-up references for consistency

Document we have split up build-environment by distro and update the
references that exist in the code base to be correct.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240603175328.3823123-7-alex.bennee@linaro.org>
5 files changed