Docs: Section on local variables

[Andrej Mitrovic]

On 4/21/12, H. S. Teoh <hsteoh at quickfur.ath.cx> wrote:
> It would be a major pain if every
> single time you need to temporarily suppress a section of code, you also
> have to hunt down every last stray variable that's now no longer
> referenced in the function and comment them out as well.

Next thing you know the compiler will start warning me when I indent
my code with uneven number of spaces!