docs(package-json): add examples for replacing dependencies with forks

[MaxBlack-dev]

Description

This PR adds documentation for how to replace a dependency with a fork using the overrides field in package.json. While the existing documentation mentioned this capability, it didn't provide any examples of how to actually do it.

Changes

• Added a new subsection "Replacing a dependency with a fork" under the overrides section
• Documented three methods for replacing dependencies:
  • Using npm: prefix to replace with a different package name
  • Using GitHub repositories (with branches, tags, or commits)
  • Using local file paths
• Included practical examples for each method
• Added example showing how to replace a transitive dependency with a fork

Context

Users were confused by the documentation stating you can replace "an existing dependency with a fork" but not explaining how. The issue thread shows multiple users asking for clarification and sharing their own discovered solutions. This PR consolidates those working examples into the official documentation.

Closes #4909