Add tag alias feature to WMI check documentation

[mrafi97]

What does this PR do?

This PR updates the WMI check documentation with the new tag aliasing feature added in #21792

Motivation

https://datadoghq.atlassian.net/browse/WINA-2173

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[github-actions]

⚠️ The qa/skip-qa label has been added with shippable changes

The following files, which will be shipped with the agent, were modified in this PR and
the qa/skip-qa label has been added.

You can ignore this if you are sure the changes in this PR do not require QA. Otherwise, consider removing the label.

List of modified files that will be shipped with the agent

wmi_check/datadog_checks/wmi_check/data/conf.yaml.example

[maycmlee]

Just some small suggestions!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.03%. Comparing base (092dffc) to head (3f5cb7f).
⚠️ Report is 9 commits behind head on master.

Additional details and impacted files

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