ExampleTestSuite: Also support mill command in addition to ./mill

[lefou]

Replace ./mill with mill in most examples, as this is easier to read. I kept the ./mill in the first simple scala project, which also describes that there is a ./mill script in each example archive.

[lihaoyi]

Should we support both? I feel like supporting 1 should be enough, and would be good to enforce some degree of consistency throughout the docsite which gets built from these test suites. If we want to use mill, we should cut over everything to mill

[lihaoyi]

I wanted to go with ./mill to remove the need for installation from the example projects, as all the zip downloads come with a ./mill script built in, so in theory anyone just needs a JVM installed and they can download the zip and follow the instructions and be ready to go

[lefou]

Yeah, I think I got your initial motivation for ./mill. Yet, I think it reads better with just mill. It also encourages to just install mill on the system and avoid dependency on some local script. It gives a newcomer a bit less hack-ish feeling. I for myself always prefer a system-installed tool over some repo-local script.

I think keeping both variants supported is not really adding inconsistency. As we explain the user that we have that script in example 1-simple-scala, I thought we should keep the ./mill at least in this example, and it will still work as an executable test.

[lihaoyi]

sounds good to me, go for it