Add links for convenience to emergency banner page
Add links for convenience to emergency banner page

[Trello]: https://trello.com/c/BUSq6xQn/1270-emergency-banner-publishing-drill

Whilst doing the regular emergency banner drill Dec 22nd, we commented
that there were not docs linked for convenience. Then thought we should
do something about that.

alphagov/govuk-developer-docs,alphagov/govuk-developer-docs,alphagov/govuk-developer-docs,alphagov/govuk-developer-docs