Docs: Section on local variables

[Jonathan M Davis]

On Wednesday, April 25, 2012 22:12:02 Andrej Mitrovic wrote:
> I'd like the warnings to be individually selectable, just like in GCC.

Having sets of warnings that you can explicitly enable makes a lot of sense, 
because it enables the programmer to have the compiler warn about stuff that 
they care about, whereas if it's something that everyone is going to consider 
a problem, then why isn't it an error? However, Walter doesn't like having a 
lot of compiler flags, and warnings pretty much only exist at all because 
people begged him for them. So, I don't see dmd ever having a bunch of warning 
flags as much as it might be desirable.

- Jonathan M Davis