website update

[Tony via Digitalmars-d-learn]

It looks like this page:

http://dlang.org/hash-map.html
Should have the override keyword added the the member functions 
in Foo:

class Foo
{
    int a, b;

    size_t toHash() { return a + b; }

    bool opEquals(Object o)
    {
        Foo foo = cast(Foo) o;
        return foo && a == foo.a && b == foo.b;
    }
}