Update zig_cross_compiling example to use the github release

[UebelAndre]

In the past there have been issues using zig from it's old home of https://git.sr.ht/~motiejus/bazel-zig-cc. It would be great if instead the example to use https://github.com/uber/hermetic_cc_toolchain

cc @illicitonion

[UebelAndre]

Ran into this issue here https://buildkite.com/bazel/rules-rust-rustlang/builds/9069#01899213-1092-4527-8b07-59b2d6b2a4fc while trying to rollout #2062

[UebelAndre]

Probably relates to #1892

[UebelAndre]

I'm disabling the check again (#2081) since jobs are failing for the same reason they did back in March. It seems like a recurring infra issue in https://git.sr.ht

[alexeagle]

I see a 3.0 is shipping right now bazelbuild/bazel-central-registry#1483
so maybe it's the right time to try this again and ping the maintainers over there if something is broken?

[UebelAndre]

I'd be happy to review a PR for anyone who wanted to try re-enabling it again.