Sync PR #990 fix to Japanese and Korean documentation

[Copilot]

PR #990 corrected a code example in the StreamingHub getting started guide, but only updated the English version. This applies the same fix to Japanese and Korean translations.

Changes

• Japanese: docs/i18n/ja/docusaurus-plugin-content-docs/current/streaminghub/getting-started.md
• Korean: docs/i18n/ko/docusaurus-plugin-content-docs/current/streaminghub/getting-started.md

Both files now correctly use userName instead of ConnectionId.toString() in the LeaveAsync() method example:

 public async ValueTask LeaveAsync()
 {
-    room.All.OnLeave(ConnectionId.toString());
+    room.All.OnLeave(userName);
     await room.RemoveAsync(Context);
 }

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Apply the fixes from pull requests to the doc for each language.</issue_title>
<issue_description>Apply the pull request fixes that have been applied to recently updated documents to each language's documentation.

• docs/docs: English (en-us)
• docs/i18n/ja/docusaurus-plugin-content-docs: Japanese
• docs/i18n/ko/docusaurus-plugin-content-docs: Korean</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Apply the fixes from pull requests to the doc for each language. #994

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.