Appio Component: Add a component description, as it is missing from papi_component_avail

[Treece-Burgess]

Pull Request Description

Currently if you run ./papi_component_avail the appio component will not have a description shown:

Compiled-in components:
Name:   appio                   

Active components:
Name:   appio                   
                                Native: 45, Preset: 0, Counters: 45

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This PR addresses this by adding a description in the component vector of appio, now ./papi_component_avail shows:

Compiled-in components:
Name:   appio                   Linux I/O system calls


Active components:
Name:   appio                   Linux I/O system calls
                                Native: 45, Preset: 0, Counters: 45

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Tested this change on a machine with an Intel Xeon Gold 6140.

Author Checklist

• Description
  Why this PR exists. Reference all relevant information, including background, issues, test failures, etc
• Commits
  Commits are self contained and only do one thing
  Commits have a header of the form: module: short description
  Commits have a body (whenever relevant) containing a detailed description of the addressed problem and its solution
• Tests
  The PR needs to pass all the tests

[dbarry9]

I am testing this pull request.

[dbarry9]

I tested these changes on Frontier (AMD Zen3 architecture), and papi_component_avail now displays the information correctly.