contrib: add "Requirements" section to PR template

[ngxson]

Changes:

• Requires keeping the acknowledge about contributing guidelines
• Requires disclosing AI usage
• Addition guide for AI agents

[am17an]

Does a commit co-authored with Claude count as disclosure?

[ngxson]

Does a commit co-authored with Claude count as disclosure?

I think co-authored doesn't specify exactly which part of the work is done by claude.

I also believe that a written disclosure encourages the contributor to be responsible / be transparent about their work.

[JohannesGaessler]

How about we make it checkboxes? Something like

• I have read and understood the contributing guidelines.
• AI was used to write parts of the code.

[ngxson]

@JohannesGaessler I find it a bit inconvenient because the editing screen requires placing an x inside the checkbox [ ]. If github allows having PR template that works like issue template, I think that would make more sense

[ngxson]

I think this is pretty much a QoL improvement for both contributors & maintainers, making it clear how to write a PR description

Since this doesn't include any functional or policy changes, could we have it merged soon @ggerganov @ggml-org/maintainers ? Thanks.