Include a link to our audits service in the warning boxes

[nventuro]

From https://github.com/OpenZeppelin/docs.openzeppelin.com/issues/47

[frangio]

Should we do this automatically or manually?

[nventuro]

I'd say it depends on what the content we add is. If its sort of intrusive, it might not fit in the middle of a complex explanation.

Also, some of our warnings are not security related, so it wouldn't really apply.