fix naming of docker images to conform to docker standards

[caoimhinuibrian]

See comments from @gongsu832 in PR #273

[gongsu832]

@caoimhinuibrian Based on #300 I think that the onnx-milr-build image is really meant for developers since it contains both llvm-project and onnx-mlir source, which makes it fairly big. Perhaps we should also create an onnx-mlir image just for end users. It will have all binaries installed without the source code so it should be fairly small. I also have a script from DLC Classic that can be adopted to run the onnx-mlir inside the docker almost exactly as if running it directly. That should make it easy for interested users to quickly try onnx-mlir on a model by typing just one command. If you think this is worthwhile, I can work on the onnx-mlir image and the accompanying script.

[doru1004]

Any updates? Please close when issue is resolved.