Sentence fix for overview.md

[inth3wild]

Why:

Closes #21991

What's being changed (if available, include any code snippets, screenshots, or gifs):

I was reading the overview.md documentation when I noticed a little grammatical error, so I decided to fix that by adding the missing correct word "by" to make the sentence valid.

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• I have reviewed my changes in staging (look for the "Automatically generated comment" and click the links in the "Preview" column to view your latest changes).
• For content changes, I have completed the self-review checklist.

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[github-actions]

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The table contains an overview of files in the content directory that have been changed in this pull request. It's provided to make it easy to review your changes on the staging site. Please note that changes to the data directory will not show up in this table.

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Content directory changes

You may find it useful to copy this table into the pull request summary. There you can edit it to share links to important articles or changes and to give a high-level overview of how the changes in your pull request support the overall goals of the pull request.

Source	Preview	Production	What Changed
codespaces/overview.md	fpt ghec	fpt ghec

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fpt: Free, Pro, Team
ghec: GitHub Enterprise Cloud
ghes: GitHub Enterprise Server
ghae: GitHub AE

[cmwilson21]

@inth3wild Thank you for opening a PR and linking it to your issue! ✨

I'll get this triaged for review! ⚡

[saritai]

@inth3wild 👋 Thanks so much for catching this! ✨ Looks great :) Will get this merged!

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