chore: add migration snippet to changeset

Author: bendersej

.changeset/replace-create-field-with-detect-fields.md

@@ -2,4 +2,14 @@
 "@simplepdf/react-embed-pdf": major
 ---
 
-Replaces `createField` with `detectFields` for automatic form field detection. This is a breaking change: the `createField` action and `CreateFieldOptions` type have been removed. If you are not using `createField`, you can safely update to this new major version.
+Replaces `createField` with `detectFields` for automatic form field detection. This is a breaking change: the `createField` action and `CreateFieldOptions` type have been removed.
+
+If you are not using `actions.createField(...)` or `sendEvent("CREATE_FIELD", ...)`, you can safely update to this new major version.
+
+```ts
+// Before (removed)
+await actions.createField({ type: "TEXT", page: 1, x: 100, y: 700, width: 200, height: 30 });
+
+// After
+await actions.detectFields();
+```