Review (and clarify, if necessary) V2 deprecation warning copy

Users who aren't familiar with the version history of onion sites seem to be misinterpreting the error, and are under the impression the deprecation warning applies to their instance of Tor Browser, rather than the onion site itself.

Although the warning does point to the support portal for further info, the learn more link is likely too subtle (and buries a lot of the explaining behind a link).

Let's review the copy here to see if there's a way we can easily clarify it – for example, adding a "What can I do about it?" section that explains in a little more detail that the issue lies with the site itself – not their browser.