WHAT
As part of allow the customer to configure a custom domain for the 3scale components a new field needs to be added to the addon form in OCM.

This field should take a domain as it entry. Validation should be carried out on the domain format.

Once the addon is installed this field can not be changed and should be optional.

Adding of this field will possibly need updates to the service definition and customer facing documentation.

HOW
New field should be added to the addOnParameters with the following flags set.

• required: false
• editable: false
• enabled: true

The name of parameter should be confirmed with the work carried out in MGDAPI-4257

TESTS
<List of related tests>

DONE

• New filed added to OCM
• Service definition updated
• user face facing documentation created.