[Areas API] Missing schema type, and two text fixes #164

Problem description

Three small items in dedicated-network-areas.yaml.

1. ServiceArea has no type: object.

    ServiceArea:
      description: Common attributes of a service area, i.e. where the network service is supported
      properties:
        id:
          ...
      required:
        - id
        - area
      anyOf:
        - required:
            - networkProfiles
        - required:
            - qosProfiles

Every other schema in this file, and in the other three API definitions in this repository, declares
type: object before properties.

2. info.description:8 reads "...where consitent coverage..." — misspelled.

3. info.description:55 reads:

coveringArea - to return the network service areas whose geographical area fully covers the input geographical area will be returned, where the input geographical area may be a circle or polygon

This sentence looks broken and is hard to follow.

Expected behavior

1. Add type: object to ServiceArea.
2. "consistent".
3. Please rewrite this sentence for clarity.

Alternative solution

None.

Additional context

None.