Docs: Fixes for code example in data validation section (#1684)

docs/data_validation.rst

@@ -15,9 +15,9 @@ following example code:
 .. code-block:: python
 
     import yaml
-    import json_schema
+    import jsonschema
 
-    schema = yaml.load("schemas/text-log-summary-artifact.yml")
+    schema = yaml.load(open("schemas/text-log-summary-artifact.yml"))
     jsonschema.validate(data, schema)
 
 This will give output telling you if your ``data`` element passes validation,