The review of std.hash package

[Jesse Phillips]

All this discussion on the use of auto in the docs made me notice 
something else about the docs I missed.

I like how ranges are documented and think digest could do the 
same. Instead of an ExampleDigest, just write the details under 
isDigest.

I don't see a need for template the constraint example (D idiom).

This would require changing examples which use ExampleDigest, but 
maybe that should happen anyway since it doesn't exist.

I don't see a reason to change my vote because of this, its all 
documentation.