Update headers with "This file was created by BestieTemplate.jl."

[lyashevska]

Related issues

Closes #282

Checklist

• [x] I am following the contributing guidelines
• [x] Tests are passing
• [x] Lint workflow is passing
• [x] Docs were updated and workflow is passing
• [x] CHANGELOG.md was updated

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (8cb70c2) to head (e0885f7).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #305 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 2 2 Lines 57 57 ========================================= Hits 57 57 ```

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[abelsiqueira]

Thanks!

@tmigot, can you review this? It's related to the issue #282 that you created.

[abelsiqueira]

I think it should be in every file that is maintained by Bestie. So the README shouldn't have a message like this. Do you feel some other file should have it?