simplify usage example

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

README.md

@@ -27,19 +27,9 @@ jobs:
   qemu:
     runs-on: ubuntu-latest
     steps:
-      -
-        name: Checkout
-        uses: actions/checkout@v2
       -
         name: Set up QEMU
-        id: qemu
         uses: docker/setup-qemu-action@v1
-        with:
-          image: tonistiigi/binfmt:latest
-          platforms: all
-      -
-        name: Available platforms
-        run: echo ${{ steps.qemu.outputs.platforms }}
 ```
 
 ## Customizing