title: Available options in the spark.read.option()
body: <p>When I read other people's python code, like, <code>spark.read.option("mergeSchema", "true")</code>, it seems that the coder has already known what the parameters to use. But for a starter, is there a place to look up those available parameters? I look up the apche documents and it shows parameter undocumented. </p>
  
  <p>Thanks. </p>