Updates the migration guide

docs/migration.md

@@ -23,3 +23,28 @@ separating the directory ignore from the file ignore.
 Document and thumbnail encryption is no longer supported. This was previously deprecated in [paperless-ng 0.9.3](https://github.com/paperless-ngx/paperless-ngx/blob/dev/docs/changelog.md#paperless-ng-093)
 
 Users must decrypt their document using the `decrypt_documents` command before upgrading.
+
+## Barcode Scanner Changes
+
+Support for [pyzbar](https://github.com/NaturalHistoryMuseum/pyzbar) has been removed. The underlying libzbar library has
+seen no updates in 16 years and is largely unmaintained, and the pyzbar Python wrapper last saw a release in March 2022. In
+practice, pyzbar struggled with barcode detection reliability, particularly on skewed, low-contrast, or partially
+obscured barcodes. [zxing-cpp](https://github.com/zxing-cpp/zxing-cpp) is actively maintained, significantly more
+reliable at finding barcodes, and now ships pre-built wheels for both x86_64 and arm64, removing the need to build the library.
+
+The `CONSUMER_BARCODE_SCANNER` setting has been removed. zxing-cpp is now the only backend.
+
+### Summary
+
+| Old Setting                | New Setting | Notes                             |
+| -------------------------- | ----------- | --------------------------------- |
+| `CONSUMER_BARCODE_SCANNER` | _Removed_   | zxing-cpp is now the only backend |
+
+### Action Required
+
+-   If you were already using `CONSUMER_BARCODE_SCANNER=ZXING`, simply remove the setting.
+-   If you had `CONSUMER_BARCODE_SCANNER=PYZBAR` or were using the default, no functional changes are needed beyond
+    removing the setting. zxing-cpp supports all the same barcode formats and you should see improved detection
+    reliability.
+-   The `libzbar0` / `libzbar-dev` system packages are no longer required and can be removed from any custom Docker
+    images or host installations.