General: Add Learn WordPress links to admin Help panel and default comment

[Infinite-Null]

Trac ticket: #62510

Description

This PR adds Learn WordPress links to improve resource discoverability in two locations:

1. The wp-admin Help panel
2. The default comment text

Why

• Helps users discover official WordPress learning resources more easily
• Provides direct access to learning materials from within wp-admin

Screenshot:

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core Committers: Use this line as a base for the props when committing in SVN:

Props ankitkumarshah.

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[github-actions]

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