PEP 748: Fix ordered list numbering

[ejm]

• Change is either:
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  • [ ] To an Accepted or Final PEP, with Steering Council approval
  • [ ] To fix an editorial issue (markup, typo, link, header, etc)
• [x] PR title prefixed with PEP number (e.g. PEP 123: Summary of changes)

Small fix for ordered list numbering. Thanks!

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[ghost]

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[AA-Turner]

Ah, this was also done in #4340. Thanks for the PR!

A