Review requirement for test-matrix.md

[JDawes-ScottLogic]

test-matrix.md doesn't appear to be included in the docs anymore. Do we still want to include this, or are the test results alongside the api documentation sufficient?

[BenLambertNcl]

I think @ColinEberhardt wanted this originally, but I think there might be value in adding this back in (seeing all the test results together). However, there are some changes that need to be made:

• I think having it on its own separate page will be best, rather than having it on the docs page with everything else (where it was originally)
• At the minute it is outputted as markdown, which jekyll converts to HTML for us. We might want to change that to just output HTML?
• The styles for the test results are added as inline styles (because of the old markdown site). This should probably be changed to be classes/ids etc, with styles in CSS.
• The generation code will need to change to reflect the change in Browser test results show in docs when no tests have been run #272, as at the moment all tests are shown for all containers.