[GOVERNANCE] Specify the governance project issues as the public medium

[kpalang]

We should specify the public medium in section 12 to be the public medium to propose amendments to all governance documents.

[kpalang]

Although we've already started using the Issues in this repository as the main medium, we should put it in writing in the governance.md document too.

@OpenIntegrationEngine/steering-committee Please comment below whether you agree or not.

[pacmano1]

Agreed, even if obvious.

[tonygermano]

Agree. If it changes in the future we can just amend the document.

[kayyagari]

I agree.

[gibson9583]

+1