docs/jobspec: Fix "task" block placement

[heitorPB]

The task block should be inside the group block. The example in the page places the task block directly under job.

[hashicorp-cla-app]

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[heitorPB]

Is it really necessary to sign a CLA for such a minor change?

[tgross]

Thanks @heitorPB!

Is it really necessary to sign a CLA for such a minor change?

Technically, yes we're supposed to require it for everything, but no one is going to complain if I just go ahead and merge this minor fix. 😀

[github-actions]

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