docs(README): update breaking change version

Author: hasezoey

README.md

@@ -13,7 +13,7 @@ Mongoose is a [MongoDB](https://www.mongodb.org/) object modeling tool designed
 
 The official documentation website is [mongoosejs.com](http://mongoosejs.com/).
 
-Mongoose 7.0.0 was released on February 27, 2023. You can find more details on [backwards breaking changes in 7.0.0 on our docs site](https://mongoosejs.com/docs/migrating_to_7.html).
+Mongoose 8.0.0 was released on October 31, 2023. You can find more details on [backwards breaking changes in 8.0.0 on our docs site](https://mongoosejs.com/docs/migrating_to_8.html).
 
 ## Support