Revert "Merge pull request #433 from alphagov/feature/simpler-nav"

This reverts commit 7d069c608e2cef1babf08505c318c6f3b40aee70, reversing
changes made to 08fa6681c7852db45034e4d98fb055f44f4ffe1c.

Bad text change. Meant to remove h3 rather than h2.