Statistics information

These links and holding information is needed as statistics announcements as a content type are going live. We need editors to know they can't publish statistics unless they're actual statistics, rather than content with numbers in it.
Add statistics guidance to What’s New
Merge pull request #177 from alphagov/feature/whats-new-update-with-stats

Add statistics guidance to What’s New
Fix markup
Remove .html from the links

Don’t need them, so avoid polluting the URL.