Add a prerequisite to Windows Runner documentation

What does this MR do?

This MR adds a prerequisite and link to the issue #38702 to Windows Runner documentation.

Why was this MR needed?

On Windows OS, the default character set is not UTF-8 if the system locale is not set to English.

As a result, problems with garbled characters and the handling of UTF-8 encoded commit messages may occur. So this MR adds a note to set the system locale to English.

What's the best way to test this MR?

1. Spin up the Windows Server.
2. Install Git and GitLab Runner.
3. Register the Runner, and configure it to use posershell as shell.
4. Set system locale to Japanese.
5. Commit the following CI/CD configuration file with this commit message: 日本語のコミットメッセージのテスト
6. You can see garbled characters in the Job log
7. Change system locale to English (United States)
8. Trigger the pipeline again.

sample-job1:
  script:
    - systeminfo
  tags:
    - windows

What are the relevant issue numbers?

Related to #38702