Use consistent language for placeholders in AWS OpenID setup

[hsnabszhdn]

Why:

These two phrases use a different language than other places. A follow-up to #34454

Closes: N/A

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

Sentence structure changes from "Add ... here" to "Replace this with ..." to be consistent with other places:

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  • For content changes, you will also see an automatically generated comment with links directly to pages you've modified. The comment won't appear if your PR only edits files in the data directory.

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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

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Source	Preview	Production	What Changed
actions/security-for-github-actions/security-hardening-your-deployments/configuring-openid-connect-in-amazon-web-services.md	fpt ghec ghes@ 3.14 3.13 3.12 3.11 3.10	fpt ghec ghes@ 3.14 3.13 3.12 3.11 3.10

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

[nguyenalex836]

@hsnabszhdn Thank you so much for opening a PR with this fix! ✨ This repo is currently in a code freeze, but we will get this merged as soon as the freeze ends on 9/16 🍏 thanks again!

[github-actions]

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