Update changelog

docs/docs/changelog/unreleased.md

@@ -1,5 +1,29 @@
 # Unreleased
 
+## 🚨 Breaking Changes
+
+### Update of crc configurations
+- **Rename:** The `Crc16.CCITT` configuration to `Crc16.XMODEM`.
+- **New Addition:** Introduced `Crc16.KERMIT`, which matches the official configuration for `Crc16.CCITT`.
+
+#### Decision Rationale
+It was intentionally decided not to reintroduce `Crc16.CCITT` with the updated configuration. While it could have been added as an alias for `Crc16.KERMIT` or a replacement, omitting `Crc16.CCITT` ensures that client code will break upon update, thereby forcing maintainers to take notice and react accordingly.
+
+#### Migration Guide
+Below are solutions to the two common scenarios that need to be addressed due to this change:
+
+1. **If you previously used `Crc16.CCITT` and expected the configuration defined [here](https://reveng.sourceforge.io/crc-catalogue/all.htm#crc.cat.crc-16-kermit):**
+
+      **Solution:** Replace all usages of `Crc16.CCITT` in your code with `Crc16.KERMIT`.
+
+2. **If you depended on or wanted to use the configuration values that `Crc16.CCITT` provided so far:**
+
+      **Solution:** Replace all usages of `Crc16.CCITT` in your code with `Crc16.XMODEM`.
+
+#### Related Issues
+- [#148](https://github.com/Nicoretti/crc/issues/148)
+- [#145](https://github.com/Nicoretti/crc/issues/145)
+
 ## 🔩  Internal
 * Update `python-environment` action
 * Add classifiers to `pyproject.toml`