feat: change "OS X" to be "macOS"

[Bashamega]

This PR updates the documentation to replace outdated references to "OS X" with the current naming convention, "macOS", for consistency and clarity.

Changes Made

• Replaced all instances of "OS X" with "macOS" in the npm documentation files.

Checklist

• Terminology is updated consistently
• No content or meaning changes outside of name update
• Docs reflect current macOS branding

References

Related to #1459

[wraithgar]

The files in content are sourced from the npm repo itself. As such you are only going to be able to change the content for the latest version of npm, in its own repo. We generally don't accept backports for documentation tweaks like this.

The bulk of the changes in content also appear to be sourced from the config definitions themselves, which are auto generated. This is a good place to start https://github.com/npm/cli/blob/latest/workspaces/config/lib/definitions/definitions.js

If you remove all the changes in content from this PR it looks like there are only a couple of changes here. That PR we may be able to land.