Small example for a TCP server that both handles IP v4 and v6

[skade]

This works quite nicely through Stream#merge.

[ghost]

I like this!

We should change CI to use --features unstable because this PR is currently failing due to the use of unstable features in examples.

[skade]

We currently have a check and a check unstable step, but that doesn't properly cover examples. :/

[ghost]

@skade Can you edit .github/workflows/ci.yml and change this:

    - name: check
      uses: actions-rs/cargo@v1
      with:
        command: check
        args: --all --bins --examples

to this:

    - name: check
      uses: actions-rs/cargo@v1
      with:
        command: check
        args: --all --bins --tests

[yoshuawuyts]

I like this example a lot!

[ghost]

Let's merge this. CI passes except for netlify, which is currently broken.