chore: add screenshots to `pubspec.yaml`
diff --git a/pubspec.yaml b/pubspec.yaml
index c3c3109..783bc5a 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -17,3 +17,7 @@
 
 dev_dependencies:
   test: ^1.16.0
+
+screenshots:
+  - description: The equatable package logo.
+    path: doc/assets/equatable_logo.png