feat: new process documentation

[nlf]

This is an attempt at defining a new, lighter, RFC process for the npm CLI.

Major changes from the old process include:

• RFCs are now submitted via issues rather than pull requests
• the RRFC is no longer a thing
• we have defined an initial response time of 2 weeks
• possible reasons for rejecting an RFC have been expanded for clarity
• clarified that this repository is not how the npm CLI team prioritizes work or defines a roadmap

and the biggest change, humans who open an RFC are also expected to handle implementation of that RFC themselves. the npm CLI team is available through several different channels for guidance and assistance, but in order to prevent this repository from becoming the place good ideas come to die we absolutely must ask our community for help in implementing them.

[nlf]

i've changed this pull request to a draft while i work on revising some things and greatly reducing the scope of this process

[thescientist13]

Would it be possible to get a quick high level call out in the description of what (if anything) is fundamentally changing with the new process proposal compared to the current process? Or maybe this is just making institutional knowledge of the process more formal and explicitly written out?

[nlf]

Would it be possible to get a quick high level call out in the description of what (if anything) is fundamentally changing with the new process proposal compared to the current process? Or maybe this is just making institutional knowledge of the process more formal and explicitly written out?

of course, thank you for the reminder! i've updated the pull request description to do just that