Create a checklist to use for new proposals

[binji]

See comment here: https://github.com/WebAssembly/proposals/issues/38#issuecomment-481446234

• Create new repository, forked from https://github.com/WebAssembly/spec
• Update WebAssembly/proposals repo
• Create tracking issue (e.g. https://github.com/WebAssembly/proposals/issues/39)
• Enable Travis CI for repo: https://travis-ci.org/account/repositories
• Enable WebHooks: https://github.com/WebAssembly/mynewproposal/settings/hooks
• Update deploy_key.enc: https://github.com/WebAssembly/reference-types/settings/keys
  • See https://gist.github.com/domenic/ec8b0fc8ab45f39403dd
  • TODO: use https://docs.travis-ci.com/user/deployment/pages/ instead?
• Add champion as owner/collaborator of repo: https://github.com/WebAssembly/mynewproposal/settings/collaboration

[chicoxyzzy]

Probably we'll also need a checklist for proposals advancement. See https://github.com/WebAssembly/design/pull/1273

[binji]

Added some steps, but I'm sure I'm missing things.