Update README.md (#432)

Fix deprecated env mention in External Release Notes

Author: DerBanko

README.md

@@ -154,11 +154,10 @@ jobs:
         if: startsWith(github.ref, 'refs/tags/')
         with:
           body_path: ${{ github.workspace }}-CHANGELOG.txt
+          repository: my_gh_org/my_gh_repo
           # note you'll typically need to create a personal access token
           # with permissions to create releases in the other repo
           token: ${{ secrets.CUSTOM_GITHUB_TOKEN }}
-        env:
-          GITHUB_REPOSITORY: my_gh_org/my_gh_repo
 ```
 
 ### 💅 Customizing