chore: fix numbering (#3508)

Vue Upgrade steps went from 1 to 3 when it should have gone from 1 to 2.

Author: liamdebeasi

docs/updating/8-0.md

@@ -56,7 +56,7 @@ npm install @ionic/react@next @ionic/react-router@next
 npm install vue@latest vue-router@latest
 ```
 
-3. Update to the latest version of Ionic 8:
+2. Update to the latest version of Ionic 8:
 
 ```shell
 npm install @ionic/vue@next @ionic/vue-router@next