Numbering applied, and H2 changed to match H2s


1) Unlike the rest of the style guide, this page had no visible structure, despite being clearly in 2 halves. Numbers have now been applied to H2s, following the format of the rest of the style guide.
2) fragment identifier URLs are now all the words that appear in the H2 (ignoring all punctuation), separated by dashes
Merge pull request #58 from ElenaFdR/patch-3

Numbering applied, and H2 changed to match H2s