docs: add breaking changes docs to migration doc (#16723)

Adds all breaking changes docs from my own PRs to the v4 migration doc.

| PR | Breaking change | Merged | In v4 migration doc |
|----|-----------------|--------|---------------------|
| [#16359](https://github.com/payloadcms/payload/pull/16359) | `feat!`
Deleted `@payloadcms/richtext-slate` — Lexical is now the only supported
rich text editor | 2026-04-23 | ✅ Added (was missing) |
| [#16414](https://github.com/payloadcms/payload/pull/16414) | `feat!`
Removed deprecated `jobs.depth` and `jobs.runHooks` config options |
2026-04-28 | ✅ Added (was missing) |
| [#16416](https://github.com/payloadcms/payload/pull/16416) | `feat!`
Removed deprecated `state: 'failed'`/`'succeeded'` job task return shape
| 2026-05-01 | ✅ Added (was missing) |
| [#16537](https://github.com/payloadcms/payload/pull/16537) | `feat!`
Bumped minimum Next.js version to 16.2.6 | 2026-05-07 | ✅ Added (was
missing) |
| [#16540](https://github.com/payloadcms/payload/pull/16540) | `feat!`
Bumped minimum Node.js version to 24.15.0 | 2026-05-08 | ✅ Added (was
missing) |
| [#16546](https://github.com/payloadcms/payload/pull/16546) | `feat!`
Removed croner `sloppyRanges` compatibility setting (stricter cron
parsing) | 2026-05-08 | ✅ Added (was missing) |
| [#16547](https://github.com/payloadcms/payload/pull/16547) | `feat!`
Removed deprecated `min`/`max` from `relationship`/`upload` fields |
2026-05-08 | ✅ Added (was missing) |
| [#16548](https://github.com/payloadcms/payload/pull/16548) |
`feat(richtext-lexical)!` Removed deprecated `HTMLConverterFeature` /
`lexicalHTML` | 2026-05-11 | ✅ Added (was missing) |
| [#16692](https://github.com/payloadcms/payload/pull/16692) | `feat!`
Bumped minimum TypeScript version to 6.0.3 | 2026-05-20 | ✅ Added (was
missing) |
| [#16693](https://github.com/payloadcms/payload/pull/16693) |
`refactor!` Removed `allowLocalizedWithinLocalized` compat flag +
`PAYLOAD_DO_NOT_SANITIZE_LOCALIZED_PROPERTY` env var | 2026-05-21 | ✅
Added (was missing) |