docs: add GitHub Actions example for container image

[kevholmes]

As requested here: go-reform/reform#299 (comment)

[kevholmes]

Hi @AlekSi - let me know if this is on track or if there's anything else you'd like to see.

[AlekSi]

Looks great. Could you also add instructions for .tar.gz please? I use something like that:

      - name: Install Go
        run: |
          sudo rm -fr /opt/hostedtoolcache/go /usr/local/go /usr/bin/go /bin/go
          curl -o go.tar.gz -L \
            https://github.com/AlekSi/golang-tip/releases/download/tip/master.linux-amd64.tar.gz
          sudo tar -C /usr/local -xzf go.tar.gz
          sudo ln -s /usr/local/go/bin/* /usr/local/bin/
          go version
          rm go.tar.gz

But that probably could be simplified.

[kevholmes]

But that probably could be simplified.

TY for the example code. Doesn't get much simpler really! The .tar.gz example is much faster to run (48 seconds faster than container example) so I called that out also.

[kevholmes]

Also, I noticed that my PR is causing a bunch of builds. Maybe adding paths-ignore: ["**.md"] to your build.yml at line ~16 like:

  pull_request:
    paths-ignore: ["**.md"]

Would help those from executing every time I sync/you approve. These builds/checks would just skip and you could still approve the PR iirc - doesn't appear as tho you'd want a full re-build for doc changes PRs.

[AlekSi]

Maybe adding paths-ignore: ["**.md"] to your build.yml

Yes, please :)

The .tar.gz example is much faster to run (48 seconds faster than container example) so I called that out also.

Maybe just say "it is faster" and put it first then? Not sure about the actual numbers

[AlekSi]

Please click that button when done:

[AlekSi]

Merged, thank you!