Delete superfluous default values

Removing `default:` entries for `land` and `water` features because:

1. These are required properties so the default is superfluous.
2. The stated default values are the wrong type - an array is given
   but it should be a string.

Author: vcschapp

schema/base/land.yaml

@@ -26,7 +26,6 @@ properties:
     properties:
       subtype:
         description: Further description of the type of land cover, such as forest, glacier, grass, or a physical feature, such as a mountain peak.
-        default: [land]
         type: string
         enum:
           - crater
@@ -44,7 +43,6 @@ properties:
           - wetland
       class:
         description: Further classification of type of landcover
-        default: [land]
         type: string
         enum:
           - archipelago

schema/base/water.yaml

@@ -26,7 +26,6 @@ properties:
     properties:
       subtype:
         description: The type of water body such as an river, ocean or lake.
-        default: [water]
         type: string
         enum:
           - canal
@@ -43,7 +42,6 @@ properties:
           - water
       class:
         description: Further description of the type of water
-        default: [water]
         enum:
           - basin
           - bay