[in_app_pur] Add screenshots to pubspec.yaml (flutter#6540)

* [in_app_pur] Add screenshots to pubspec.yaml

* Style fix

Co-authored-by: Stuart Morgan <[email protected]>

Author: szakarias

packages/in_app_purchase/in_app_purchase/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 3.1.1
+
+* Adds screenshots to pubspec.yaml.
+
 ## 3.1.0
 
 * Adds macOS as a supported platform.

packages/in_app_purchase/in_app_purchase/pubspec.yaml

@@ -2,7 +2,7 @@ name: in_app_purchase
 description: A Flutter plugin for in-app purchases. Exposes APIs for making in-app purchases through the App Store and Google Play.
 repository: https://github.com/flutter/plugins/tree/main/packages/in_app_purchase/in_app_purchase
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+in_app_purchase%22
-version: 3.1.0
+version: 3.1.1
 
 environment:
   sdk: ">=2.12.0 <3.0.0"
@@ -34,3 +34,9 @@ dev_dependencies:
     sdk: flutter
   plugin_platform_interface: ^2.0.0
   test: ^1.16.0
+
+screenshots:
+  - description: 'Example of in-app purchase on ios'
+    path: doc/iap_ios.gif
+  - description: 'Example of in-app purchase on android'
+    path: doc/iap_android.gif