Small error about the naming

[xiu-cs]

Thanks for your great work! When I try to reproduce this repo, I find some small issues.

1. exec: make test_contents. (The first issue is due to inconsistent file naming.)

2. exec: make test_docker (similar as issue 1)
   

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In fact, if all the names are changed to lowercase, there won’t be any issues. (Docker image names must be in lowercase)