Fix image platform for arm image

[leakingtapan]

Fix: #345

Fixing the multi-arch container image build by properly annotate the image manifest for each architectures (arm64 and amd64). So that the image platform is correct.

Testing
Built test image and pushed to my personal dockerhub registry:

docker manifest inspect chengpan/ignite:v0.7.0-25-9c998301147a44-arm64
{
   "schemaVersion": 2,
   "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
   "manifests": [
      {
         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
         "size": 529,
         "digest": "sha256:81d44b341961ca83f74fcaad5b88f6750413f4de96b20df561566cf3af8ec5ce",
         "platform": {
            "architecture": "arm64",
            "os": "linux"
         }
      }
   ]
}

[leakingtapan]

@stealthybox the doc site link check seems an existing issue

[stealthybox]

@leakingtapan yes -- don't worry about the link checker 👍

[darkowlzz]

Updating the manifest for the images at the end LGTM!

Thanks for fixing it.