Add Testing steps for version 7.8.1

Author: Aljullu

docs/testing/releases/781.md

@@ -0,0 +1,16 @@
+## Testing notes and ZIP for release 7.8.1
+
+Zip file for testing: [woocommerce-gutenberg-products-block.zip](https://github.com/woocommerce/woocommerce-blocks/files/8891266/woocommerce-gutenberg-products-block.zip)
+
+## Feature plugin and package inclusion in WooCommerce
+
+###  Fix PHP notice in Mini Cart when prices included taxes. ([6537](https://github.com/woocommerce/woocommerce-blocks/pull/6537))
+
+1. Go to _WooCommerce_ > _Settings_ and check _Enable tax rates and calculations_.
+2. Go to the _Tax_ tab in the settings and check _Yes, I will enter prices inclusive of tax_ and _Display prices during cart and checkout: Including tax_.
+3. Add the Mini Cart block to a post or page.
+4. Visit that post or page in the frontend, and verify there isn't a PHP notice.
+
+| Before                                                                                                                                    | After                                                                                                                                      |
+|-------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------|
+| ![Screenshot showing a PHP warning](https://user-images.githubusercontent.com/3616980/172639823-1b671ac0-58ea-4f4b-9b00-aa481d4acd72.png) | ![Screenshot showing no PHP warning](https://user-images.githubusercontent.com/3616980/172639911-7a1416fe-f49d-4c58-90b7-7e07637b1777.png) |

docs/testing/releases/README.md

@@ -73,6 +73,7 @@ Every release includes specific testing instructions for new features and bug fi
 -   [7.6.0](./760.md)
 -   [7.7.0](./770.md)
 -   [7.8.0](./780.md)
+-   [7.8.1](./781.md)
 
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