fix nomad job allocs command name

[lgfa29]

#11242 added the nomad job allocs command, but the command name was set to job allocations. The command name is displayed in the error message.

Before:

$ nomad job allocs
This command takes one argument: <job>
For additional help try 'nomad job allocations -help'

After:

$ nomad job allocs
This command takes one argument: <job>
For additional help try 'nomad job allocs -help'

No changelog since this is still an unreleased feature.

[notnoop]

Good catch!

[github-actions]

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