Embedded example data from csv-schema causes MetaStore failures

Example values are included in the doc for each field to show what was used to infer the type of a column in the csv-schema command. If this text is too long or includes illegal characters, it will cause a failure in the MetaStore. At a minimum, we should truncate long example values. I'm not sure how to fix the unicode issue. Maybe remove all but a known-safe character set?