Documentation on options

Key: options
	This keyword is often used to specify extra processing options
	to a task. Where several options are to be given, they are
	separated by commas. Minimum match is used.

	Some common options are:
	  nocal    This option is used by uv programs which apply
	           antenna gain corrections to the data (assuming the
	           appropriate tables are present). This option disables
	           this correction step.
	  nopol    This option is used by uv programs which apply
	           instrumental polarisation corrections to the data (assuming
	           the appropriate tables are present). This option disables
	           this step.