Add instructions on how to submit a CFP

[marcoieni]

Add instructions on how to submit a CFP to:

• Rust Italia/Torino
• Rust Milano
• Rust Roma

Please, ask the Community admin if they agree 👍

How to submit a cfp?

You tell me 😉

It can be anything:

• from submitting an issue or a PR to https://github.com/rust-italia/cfp
• DM someone

[lu-zero]

• We use the github issue template and mimic what rust-lang does for the rfcs (mainly what we have in the cfp repo maybe tweaked a bit to aggregate over all the local meetups)
• Provide a list of volunteers to contact to hash out ideas, help fill in the issue/pr.