cpupower: add page

[toydotgame]

• The page (if new), does not already exist in the repository.
• The page is in the correct platform directory (common/, linux/, etc.)
• The page has 8 or fewer examples.
• The PR title conforms to the recommended templates.
• The page follows the content guidelines.
• The page description includes a link to documentation or a homepage (if applicable).

Version of the command being documented (if known): 5.17-1

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Last PR (#7975) got borked by Git. Starting again.

[navarroaxel]

It's not a good practice send PRs from your main. You should keep your main in sync with the tldr-pages:main, then create feature branches and send PRs from them. Then you have a clean branch to create more PRs. Let as-is for now. you can change this after merge this PR.