Fix broken "config generate" (#975).

borgmatic/config/generate.py

@@ -41,6 +41,7 @@ def schema_to_sample_configuration(schema, level=0, parent_is_sequence=False):
     '''
     schema_type = schema.get('type')
     example = schema.get('example')
+
     if example is not None:
         return example
 

borgmatic/config/schema.yaml

@@ -1051,6 +1051,7 @@ properties:
                         "tar" format. Be aware that Borg does its own
                         compression as well, so you may not need it in both
                         places.
+                    example: none
                 ssl_mode:
                     type: string
                     enum: ['disable', 'allow', 'prefer',