The randomized domain from `repo create` looks like a mistake

[angeloashmore]

Is your feature request related to a problem? Please describe.

prismic repo create assigns a random domain (for example, 0b4d7321). This is intentional. But the help text does not say so.

Users and AI agents expect the domain to match the repository name. When they see the random domain, they think the command failed. Then they take bad recovery steps. In one observed session, an agent recommended that the user delete the repository and create a new one in the web UI.

Describe the solution you'd like

Document the behavior in the help text of prismic repo create:

• The CLI generates a random domain.
• The user cannot select or change the domain.
• The command output shows the domain.

Describe alternatives you've considered

Additional context