Update changelog and release notes

Author: alexeyr

CHANGELOG.md

@@ -33,6 +33,10 @@ Changes since the last non-beta release.
 
 - Deprecated `defer_generated_component_packs` configuration option. You should use `generated_component_packs_loading_strategy` instead. [PR 1712](https://github.com/shakacode/react_on_rails/pull/1712) by [AbanoubGhadban](https://github.com/AbanoubGhadban).
 
+### Changed
+
+- The global context is now accessed using `globalThis`. [PR 1727](https://github.com/shakacode/react_on_rails/pull/1727) by [alexeyr-ci2](https://github.com/alexeyr-ci2).
+
 ### [15.0.0-alpha.2] - 2025-03-07
 
 See [Release Notes](docs/release-notes/15.0.0.md) for full details.

docs/release-notes/15.0.0.md

@@ -68,6 +68,11 @@ Major improvements to component and store hydration:
 - If you were previously using `defer_generated_component_packs: false`, use `generated_component_packs_loading_strategy: :sync` instead
 - For optimal performance with Shakapacker ≥ 8.2.0, consider using `generated_component_packs_loading_strategy: :async`
 
+### `globalThis`
+
+[`globalThis`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/globalThis) is now used in code.
+It should be available in browsers since 2020 and in Node, but in case your environment doesn't support it, you'll need to shim it using [globalthis](https://www.npmjs.com/package/globalthis) or [core-js](https://www.npmjs.com/package/core-js).
+
 ## Store Dependencies for Components
 
 When using Redux stores with multiple components, you need to explicitly declare store dependencies to optimize hydration. Here's how: