docs: remove trailing newlines in code blocks

[muzimuzhi]

Why:

Closes: #27989

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

Several trailing and a single beginning newlines inside markdown code blocks are removed.

Check off the following:

• I have reviewed my changes in staging, available via the View deployment link in this PR's timeline.

  • 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.

• For content changes, I have completed the self-review checklist.

[github-actions]

👋 Hey there spelunker. It looks like you've modified some files that we can't accept as contributions. The complete list of files we can't accept are:
.devcontainer/**
.github/actions-scripts/**
.github/workflows/**
.github/CODEOWNERS
assets/fonts/**
data/graphql/**
Dockerfile*
src/**
lib/redirects/**
package*.json
scripts/**
content/actions/deployment/security-hardening-your-deployments/**

You'll need to revert all of the files you changed in that list using GitHub Desktop or git checkout origin/main <file name>. Once you get those files reverted, we can continue with the review process.

[github-actions]

Automatically generated comment ℹ️

This comment is automatically generated and will be overwritten every time changes are committed to this branch.

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
actions/using-workflows/events-that-trigger-workflows.md	fpt ghec ghes@ 3.10 3.9 3.8 3.7 3.6 ghae	fpt ghec ghes@ 3.10 3.9 3.8 3.7 3.6 ghae
admin/administering-your-instance/command-line-utilities.md	ghes@ 3.10 3.9 3.8 3.7 3.6	ghes@ 3.10 3.9 3.8 3.7 3.6
code-security/code-scanning/using-codeql-code-scanning-with-your-existing-ci-system/migrating-from-the-codeql-runner-to-codeql-cli.md	fpt ghec ghes@ 3.10 3.9 3.8 3.7 3.6 ghae	fpt ghec ghes@ 3.10 3.9 3.8 3.7 3.6 ghae
code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file.md	fpt ghec ghes@ 3.10 3.9 3.8 3.7 3.6	fpt ghec ghes@ 3.10 3.9 3.8 3.7 3.6
code-security/supply-chain-security/understanding-your-software-supply-chain/using-the-dependency-submission-api.md	fpt ghec ghes@ 3.10 3.9 3.8 3.7	fpt ghec ghes@ 3.10 3.9 3.8 3.7
codespaces/setting-up-your-project-for-codespaces/adding-a-dev-container-configuration/setting-up-your-java-project-for-codespaces.md	fpt ghec	fpt ghec
issues/planning-and-tracking-with-projects/automating-your-project/automating-projects-using-actions.md	fpt ghec ghes@ 3.10 3.9 3.8	fpt ghec ghes@ 3.10 3.9 3.8
migrations/using-github-enterprise-importer/migrating-organizations-with-github-enterprise-importer/migrating-organizations-from-githubcom-to-github-enterprise-cloud.md	fpt ghec ghes@ 3.10 3.9 3.8 3.7 3.6	fpt ghec ghes@ 3.10 3.9 3.8 3.7 3.6

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

[muzimuzhi]

Please note that changes to the data directory will not show up in this table.

I've also reviewed all the pages affected by the changes to data dir.

[cmwilson21]

@muzimuzhi Thanks for opening an issue and submitting a PR! We appreciate the details you've provided 👍

I'll get this triaged for review! ⚡

[subatoi]

Thank you for fixing this (and for raising an issue)—it's very much appreciated ✨

[github-actions]

Thanks very much for contributing! Your pull request has been merged 🎉 You should see your changes appear on the site in approximately 24 hours. If you're looking for your next contribution, check out our help wanted issues ⚡