Maths on vote majority

[vstinner (Victor Stinner)]

@vstinner

For me PEP 8015, I propose to change votes:

• Promote a contributor as core developer: majority (2/3)
• Vote on a PEP: majority (2/3)
• Modify the governance PEP: “everybody has to agree” (4/5)

I modified my PEP 8015 exactly like that, see Annex: Summary on votes.