Clarify Codespaces billing for forks

[SR0725]

OpenAI Codex generated this pull request. External contributors cannot apply repository labels, so a maintainer will need to add llm-generated.

Why:

Fixes #41324

The billing conditions currently imply that any personal fork of an organization repository can produce an organization-paid codespace. The issue confirms that this applies only to organization-owned forks.

What's being changed:

The reusable now says that a codespace can come from an organization's repository or an organization-owned fork. This keeps personal forks owned by outside collaborators out of the organization-paid case.

SME review needed: Please confirm the billing boundary in the edited second bullet. The wording follows the engineer-backed suggestion in #41324.

Validation:

• npm run lint-content -- --paths data/reusables/codespaces/when-an-org-pays.md
• npm run build
• CHANGED_FILES=content/codespaces/managing-codespaces-for-your-organization/choosing-who-owns-and-pays-for-codespaces-in-your-organization.md npm run test -- src/content-render/tests/render-changed-and-deleted-files.ts

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

Note: Please update the URL for your staging server or codespace.

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

Source	Review	Production	What Changed
codespaces/managing-codespaces-for-your-organization/choosing-who-owns-and-pays-for-codespaces-in-your-organization.md	fpt ghec	fpt ghec	from reusable

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

🤖 This comment is automatically generated.