Merge branch 'develop' into feature/MARS-962

Author: danovaro

share/metkit/axis.yaml

@@ -49,3 +49,4 @@ axes:
     - resolution
     - year
     - month
+    - obsgroup

share/metkit/language.yaml

@@ -355,6 +355,7 @@ _field: &_field
         val: 'prod'
 
   dataset:
+    category: data
     multiple: false
     type: enum
     values:
@@ -1331,7 +1332,6 @@ disseminate:
     type: any
 
   use:
-    category: data
     flatten: false
     multiple: true
     type: enum