second draft: add Bitfields to D

[Richard (Rikki) Andrew Cattermole]

On 23/04/2024 1:01 PM, Walter Bright wrote:
> https://github.com/WalterBright/documents/blob/dcb8caabff76312eee25bb9aa057774d981a5bf7/bitfields.md

Randomly came across people talking about C bitfields, and how the 
non-defined bit layout is causing them problems.

https://twitter.com/__phantomderp/status/1786628836953604201

Turns out even they think they need control over the layout including 
predictable LSB..MSB byte by byte definition.

Making it default to C for the layout is not a good addition to the 
language.