task: #3587744 Add FR + ES translations for the new write-side semantics docs
The MR that introduced "Override write semantics" and "Known limitation: sequence shrinks" in docs/domain_config/index.md was merged before the translations were updated; this follow-up keeps the FR/ES locales in sync with the English reference.
Translation conventions match the existing files:
- "override" -> "surcharge" / "sobrescritura"
- Technical terms in English (class names, hooks, config keys, Drupal/Symfony API, ConfigFormBase, EntityForm, etc.).
- Code blocks unchanged.
Closes #3587744