Update alpine package name in installation guide

[v1r7u]

PR Summary

The "Installing PowerShell on Linux" has a wrong name of the alpine package. The PR corrects it.

The change is minor, but the current state of documentation led me to incorrect docker-container, that I had to debug for a while.

PR Context

Select the type(s) of documents being changed.

Cmdlet reference & about_ topics

• Version 7.x preview content
• Version 7.0 content
• Version 6 content
• Version 5.1 content

Conceptual articles

• Fundamental conceptual articles
• Script sample articles
• DSC articles
• Gallery articles
• JEA articles
• WMF articles
• SDK articles

[opbld34]

Docs Build status updates of commit 3a085d0:

✅ Validation status: passed

File	Status	Preview URL	Details
reference/docs-conceptual/install/Installing-PowerShell-Core-on-Linux.md	✅Succeeded	View (powershell-3.0) View (powershell-4.0) View (powershell-5.0) View (powershell-5.1) View (powershell-6) View (powershell-7) View (powershell-7.x)

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