Document the Che-Code's port auto-exposure feature

[azatsarynnyy]

Is your enhancement related to a problem? Please describe

There's a nice feature in Che-Code that allows to automatically expose three ports for the user's application.
So, the user doesn't need to care about defining an endpoint in a project devfile.

The problem is that the feature is not documented and it may be hard to understand how to use it.

Describe the solution you'd like

Document the Che-Code's port auto-exposure feature.

Describe alternatives you've considered

No response

Additional context

• Che-Code built-in extension https://github.com/che-incubator/che-code/tree/main/code/extensions/che-port
• Internal endpoints https://github.com/eclipse-che/che-operator/blob/d5e74996ea1628e6a014d39ba218d1c2b263b6d1/editors-definitions/che-code-latest.yaml#L115-L135