Minor bugs in example

[metonymic-smokey]

Thanos, Prometheus and Golang version used: latest, 2.29, 1.16

What happened:

1. In examples/interactive/interactive_test.go, the TestReadOnlyThanosSetup , the message in t.Skip should state "comment" instead of "uncomment".
2. The docs also lack the steps to run the interactive example. Using a go test command may not come easily to newcomers to Go.

What you expected to happen:
Docs in the tutorial section detailing how to run the interactive example.

[metonymic-smokey]

@yeya24 here is the issue we discussed about.
Could you please assign me?
Thanks!