Number RFCs by order of proposal

[esoterra]

Assign each RFC a number in order of when it was proposed that is put as the beginning of the file name e.g. 000-rfc-process.md.

• Users will be able to tell what order RFCs were proposed in
• Users will be able to reference individual RFCs more easily (e.g. "go look at RFC 001")
• RFCs will be ordered in the accepted/ folder by order of proposal
• RFCs which change the RFC process can be more clear (e.g. "RFCs after 001 MUST...")

[bjorn3]

Rust uses the PR number.

[esoterra]

That would work.