Add EIP-5793: eth/68: Add transaction type to tx announcement

[MariusVanDerWijden]

trafficstars

When opening a pull request to submit a new EIP, please use the suggested template: https://github.com/ethereum/EIPs/blob/master/eip-template.md

We have a GitHub bot that automatically merges some PRs. It will merge yours immediately if certain criteria are met:

• The PR edits only existing draft PRs.
• The build passes.
• Your GitHub username or email address is listed in the 'author' header of all affected PRs, inside .
• If matching on email address, the email address is the one publicly listed on your GitHub profile.

[eth-bot]

Hi! I'm a bot, and I wanted to automerge your PR, but couldn't because of the following issue(s):

---

(fail) eip-5793.md

classification
newEIPFile

• File with name EIPS/eip-5793.md is new and new files must be reviewed
• This PR requires review from one of [@lightclient, @axic, @samwilsn]