docs: update changelog

Author: kazupon

CHANGELOG.md

@@ -6,7 +6,47 @@ This changelog is generated by [GitHub Releases](https://github.com/intlify/vue-
 
 ## What's Changed
 
-### 💥 Breaking Changes
+### Deprecate Legacy API mode
+
+The Legacy API mode was the API mode compatible with v8 for Vue 2. When v9 was released, the Legacy API was provided to smooth the migration from v8 to v9.
+
+Legacy API mode will be deprecated in v11, as previous vue-i18n releases have already provided the following to support migration to Composition API mode
+
+- Migration from Legacy API mode to Composition API mode, see the [docs](https://vue-i18n.intlify.dev/guide/migration/vue3.html)
+- Composition API usage, see the [docs](https://vue-i18n.intlify.dev/guide/advanced/composition.html)
+
+For compatibility, Legacy API mode still works in v11, but will be removed entirely in v12, so Legacy API mode will not work after that version.
+
+### Deprecate Custom Directive `v-t`
+
+The advantage of `v-t` was that it could optimize performance using the vue compiler transform and the pre-translation of `vue-i18n-extension`.
+
+This feature was supported from Vue 2.
+About details see the blog [article](https://medium.com/@kazu_pon/performance-optimization-of-vue-i18n-83099eb45c2d)
+
+In Vue 3, due to the Composition API, the pre-translation of [`vue-i18n-extension`](https://github.com/intlify/vue-i18n-extensions) is now limited only for global scope.
+
+In addition, Vue 3 Virtual DOM optimization has been introduced, and the optimization provided by `vue-i18n-extension` is no longer very effective. We need to require settings for SSR, the benefits of using `v-t` have disappeared. And DX of templates using `v-t` is not good. Custom directives do not work with key completion in editors (e.g. vscode).
+
+For compatibility, `v-t` mode still works in v11, but will be removed entirely in v12, so `v-t` will not work after that version.
+
+### Drop `tc` and `$tc` for Legacy API mode
+
+These APIs had already deprecated in warning about being dropped in v11. docs [says](https://vue-i18n.intlify.dev/guide/migration/breaking10.html#deprecate-tc-and-tc-for-legacy-api-mode)
+
+### Vue I18n maintenance Status
+
+Vue I18n v8 is no longer supported after 2025. Vue I18n v9 is in maintenance mode after 2025.
+
+With the release of Vue I18n v11, that version will become mainstream.
+
+The maintenance detail status of Vue I18n v9 and Vue I18n v10 is as follows:
+
+<img src="https://raw.githubusercontent.com/intlify/vue-i18n/master/docs/public/lifecycle2025.svg" />
+
+You can check the maintenance status on the [docs](https://vue-i18n.intlify.dev/guide/maintenance.html)
+
+### ❗ Braeking Changes
 
 - feat!: deprecate Legacy API mode by @kazupon in https://github.com/intlify/vue-i18n/pull/2016
 - breaking: drop `$tc` and `tc` by @kazupon in https://github.com/intlify/vue-i18n/pull/2017
@@ -33,7 +73,7 @@ This changelog is generated by [GitHub Releases](https://github.com/intlify/vue-
 - Fix another typo by @shaedrich in https://github.com/intlify/vue-i18n/pull/2041
 - docs: add maintenance status by @kazupon in https://github.com/intlify/vue-i18n/pull/2044
 
-## New Contributors
+## 👋 New Contributors
 
 - @chrissyast made their first contribution in https://github.com/intlify/vue-i18n/pull/2003
 - @Sammuel09 made their first contribution in https://github.com/intlify/vue-i18n/pull/1998