296 update proposal process

[deemp]

• closes #296

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PR-Codex overview

This PR updates the proposal template and process in the normalizer repository to reflect changes in authorship and review responsibilities.

Detailed summary

• Updated author field in proposal template to allow multiple authors
• Changed wording to reflect that authors submit proposals for discussion
• Updated labels and actions in the proposal process to clarify author responsibilities

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[0crat]

@deemp Thanks for the contribution! You've earned +10 points for this: +30 as a basis; -10 for too few (0) comments; -10 for too few (10) hits-of-code. Please, keep them coming. Your running balance is +63.

[0crat]

@fizruk Thanks for the review! You've earned +5 points for this: +25 as a basis; -10 for too few (0) comments; -10 for too few (10) hits-of-code. Your running balance is +238.