"Automate Updating Dependencies" documentation improvements

[MilanKovacic]

Documentation issue

• Reporting a typo
• Reporting a documentation bug
• Documentation improvement
• Documentation feedback

Is there a specific documentation page you are reporting?

Automate updating dependencies

Additional context or description

From reading the documentation (and based on some questions in the Discord channel), it can be misleadingly interpreted that the migration procedure updates all packages, or all packages managed by the plugins (e.g., @nx/nest - nest packages). I've observed several questions where people were surprised that nx migrate did update @nx/nest package, but not nest packages to their latest versions.
Clarification is needed to specify that nx migrate focuses on Nx-related packages, and infrastructure, and will only upgrade plugin-managed packages if required (as specified by migrations.json file).

For example, here is the excerpt from the documentation:

The nx migrate command helps by automating the process of updating:

• package versions in your package.json