add RELEASE_NOTES.md

RELEASE_NOTES.md

+## 🚀 New Features
+-  Description of the new feature 1.
+-  Description of the new feature 2.
+
+## 🐛 Bug Fixes
+-  Description of the bug fix 1.
+-  Description of the bug fix 2.
+
+## ⚡ Performance Improvements
+-  Description of the performance improvement 1.
+-  Description of the performance improvement 2.
+
+## 📦 Dependencies updates
+-  Updated dependency: PackageName 1 to version x.x.x.
+-  Updated dependency: PackageName 2 to version x.x.x.
+
+## ✨ Other Changes
+- Another minor change 1.
+- Another minor change 2.
+
+## 🚨 Changes in ENV variables
+-  Added new environment variable: ENV_VARIABLE_NAME with value.
+-  Updated existing environment variable: ENV_VARIABLE_NAME to new value.
+
+**Full list of the ENV variables**: [v1.2.3](https://github.com/blockscout/frontend/blob/v1.2.3/docs/ENVS.md)
+
+## 🦄 New Contributors
+- @contributor1 made their first contribution in https://github.com/blockscout/frontend/pull/1
+- @contributor2 made their first contribution in https://github.com/blockscout/frontend/pull/2
+
+---
+
+**Full Changelog**: https://github.com/blockscout/frontend/compare/v1.2.2...v1.2.3