docs: add example when using workdir along with upload-artifact (#366)

when using workdir, goreleaser creates dist folder inside of workdir, but upload-artifact action's path only matching from git_root dir

Author: zdtsw

README.md

@@ -138,14 +138,15 @@ purpose. You can do that with the [actions/upload-artifact](https://github.com/a
         with:
           version: latest
           args: release --rm-dist
+          workdir: myfolder
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       -
         name: Upload assets
         uses: actions/upload-artifact@v3
         with:
           name: myapp
-          path: dist/*
+          path: myfolder/dist/*
 ```
 
 ### Install Only