Rollup merge of #129003 - Voultapher:improve-ord-docs, r=workingjubilee

Improve Ord docs

- Makes wording more clear and re-structures some sections that can be overwhelming for someone not already in the know.
- Adds examples of how *not* to implement Ord, inspired by various anti-patterns found in real world code.

Many of the wording changes are inspired directly by my personal experience of being confused by the `Ord` docs and seeing other people get it wrong as well, especially lately having looked at a number of `Ord` implementations as part of #128899.

Created with help by `@orlp.`

r​? `@workingjubilee`