[web2py] Small typo in Example 18

[Bruno da Silva Assis]

Hi!

I was looking thru the Examples page when I stumbled upon a small typo on
Example 18:

5. <h2>{{number.capitalize()}}<h2>

Note that the closing tag should be </h2>.

I've noticed this because in Internet Explorer 8 it renders in a quite
strange way. In Firefox (and probably WebKit) it renders OK, so you should
have missed it.

That's all.
Keep up the great work, web2pyers ;)