[ISO/CS C++2023] Adjust presentation of bibliography

[jensmaurer]

• Bibliography Please number each item in the bibliography starting with [1]. See an example in the ISO model standard https://www.iso.org/files/live/sites/isoorg/files/developing_standards/docs/en/model_document-rice_model.pdf
• Bibliography Please remove this sentence from the bibliography. This can be moved to the relevant part in the document where ISO/IEC 10967-1:2012 is cited.

[jensmaurer]

@tkoeppe , please cherry-pick aa595cb for the first item.

[tkoeppe]

Done, thank you!