[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

docs/design_doc.md

@@ -246,8 +246,9 @@ One region table can refer to multiple sets of Regions. But each row can map to
 If any of `region`, `region_key` and `instance_key` are defined, they all MUST be defined. A table not defining them is still allowed, but it will not be mapped to any spatial element.
 
 In `spatialdata-io` we use a consistent naming scheme for the `region_key` and `instance_key` column, which is suggested (but not required):
-- we use the name `'region'` as the default name for the `region_key` column;
-- we use the name `'instance_id'` as the default name for the `instance_key` column.
+
+-   we use the name `'region'` as the default name for the `region_key` column;
+-   we use the name `'instance_id'` as the default name for the `instance_key` column.
 
 ### Summary