Add tron namespace and CAIP-2 specification

[danroc]

This PR adds the tron namespace and its CAIP-2 specification.

Rendered files:

• README
• CAIP-2

[bumblefudge]

Made minor comments for formatting and made obvious stuff painfully explicit (it's been my experience that these get read very quickly!).

One editorial aside that might be worth mentioning is that proper handling of large ChainIDs is a little hard to guarantee/assume. I remember there have been many discussions over the years (mostly linked from this eth-mag thread ) about what the proper or optimal maximum value should be for chainId, but I also remember (can't find the link right now) that viem and other major libraries validate chainIds internally, making a defacto maximum value of... whatever library a given dapp uses 😅

This is all probably overkill for a TRON namespace, but just a possible footnote if you're already/also tracking that thread elsewhere...

[bumblefudge]

@obstropolos care to double-check i'm not missing anything?