Add PowerShell snippet for setting TARGET_API_URL environment variable

[rufer7]

Why:

PowerShell snippet is missing for setting TARGET_API_URL environment variable

Closes: #36799

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

Check off the following:

• A subject matter expert (SME) has reviewed the technical accuracy of the content in this PR. In most cases, the author can be the SME. Open source contributions may require an SME review from GitHub staff.
• The changes in this PR meet the docs fundamentals that are required for all content.
• All CI checks are passing and the changes look good in the review environment.

[github-actions]

How to review these changes 👓

Thank you for your contribution. To review these changes, choose one of the following options:

• Spin up a codespace
• Set up a local development environment

A Hubber will need to deploy your changes internally to review.

Table of review links

⚠️ Warning: Our review server is experiencing latency issues.

The table shows the files in the content directory that were changed in this pull request. This helps you review your changes on the review server. Changes to the data directory are not included in this table.

Source	Review	Production	What Changed
migrations/using-github-enterprise-importer/migrating-between-github-products/migrating-organizations-from-githubcom-to-github-enterprise-cloud.md	fpt ghec ghes@ 3.16 3.15 3.14 3.13 3.12	fpt ghec ghes@ 3.16 3.15 3.14 3.13 3.12	from reusable
migrations/using-github-enterprise-importer/migrating-from-azure-devops-to-github-enterprise-cloud/migrating-repositories-from-azure-devops-to-github-enterprise-cloud.md	fpt ghec ghes@ 3.16 3.15 3.14 3.13 3.12	fpt ghec ghes@ 3.16 3.15 3.14 3.13 3.12	from reusable
migrations/using-github-enterprise-importer/migrating-from-bitbucket-server-to-github-enterprise-cloud/migrating-repositories-from-bitbucket-server-to-github-enterprise-cloud.md	fpt ghec ghes@ 3.16 3.15 3.14 3.13 3.12	fpt ghec ghes@ 3.16 3.15 3.14 3.13 3.12	from reusable

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

🤖 This comment is automatically generated.

[subatoi]

Many thanks @rufer7, we'll review this as soon as we can

[subatoi]

@rufer7 Many thanks for spotting this and raising a PR. This is a worthwhile addition but would you be willing to amend it slightly so it matches the other formatting on the page (via other reusables)? So this whole reusable would become:

1. If you're migrating to {% data variables.enterprise.data_residency %}, for convenience, set an environment variable for the **base API URL** for your enterprise. 

   * If you're using Terminal, use the `export` command.

      ```shell copy
      export TARGET_API_URL="https://api.{% data 
      variables.enterprise.data_residency_example_domain %}"
      ```

   * If you're using PowerShell, use the `$env` command.

      ```shell copy
      $env:TARGET_API_URL="https://api.{% data 
      variables.enterprise.data_residency_example_domain %}"
      ```

[rufer7]

@subatoi sure, I'll do so today

[rufer7]

@subatoi done

[subatoi]

Many thanks, @rufer7! Really appreciate you spotting this, raising an issue, and making those changes. I'll get this merged for you now ✨

[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 ⚡

[rufer7]

Thanks @subatoi for the review and for merging! I usually try to create PRs and issues instead of just issues ;)