Build secrets docs lie? #2026

Link to the affected page or pages
(https://fly.io/docs/apps/build-secrets/

Describe what parts of the doc need improvement
You say "You can set secrets for your applications, but these are only available at run-time. They aren’t available when building your Docker image without a little extra work."

Ok. So I expect that I can use app secrets in build stage.
Then why in step 2 you say that some value should be provided? It's already in app secret (I just added it through UI in section "Secrets" of my application) and I expect that I can just use it with "a little extra work".

fly deploy \
    --build-secret MY_SUPER_SECRET=some_value

From this docs I don't understand how to use my application secrets in build stage.
I use GitHub actions like:

    steps:
      - uses: actions/checkout@v4
      - uses: superfly/flyctl-actions/setup-flyctl@master
      - run: flyctl deploy --remote-only -c fly.production.toml
        env:
          FLY_API_TOKEN: ${{ secrets.FLY_PROD_APP_TOKEN }}

So I need to duplicate secret in GitHub to pass its value to command flyctl deploy and can't just use it?
Like the following?

    steps:
      - uses: actions/checkout@v4
      - uses: superfly/flyctl-actions/setup-flyctl@master
      - run: flyctl deploy --remote-only -c fly.production.toml --build-secret MY_SUPER_SECRET=${{ secrets.FLY_PROD_APP_TOKEN }}
        env:
          FLY_API_TOKEN: ${{ secrets.FLY_PROD_APP_TOKEN }}