Richard Neill authored Apr 20, 2022 and Diego Sueiro committed Apr 25, 2022

This patch provides more precision about the minimal requirements for
contributions, and clarifies that the automated QA checks can only validate a
subset of those requirements.

In addition, the suggested reporting of Gitlab issues is expanded from relating
to bug-reports only, to also include security concerns and feature requests.

The contributing page is also slightly restructured for more clarity.

Issue-Id: SCM-4394
Signed-off-by: Richard Neill <richard.neill@arm.com>
Change-Id: I40b0d1daff14e1db0ff2be4aabe5bf2794c379cb