Add month/year of testing to results

[birjj]

Given that the browsers aren't tested all together, it's important to make it clear when each test was done so that readers can have an idea of how up-to-date each result is. This PR adds that information.

The dates are taken from the commit history, more specifically:

• Safari: fe2149e4
• Edge: cf4e158d
• Others: 7770466d

For visual reference, the update looks like this:

[stevefaulkner]

@birjolaxew thnks but gonna hold off on this for now as I am updating results and have modded the % for browsers in update state