Added default setting for prism boundary type parameter to docstring
Added default setting for prism boundary type parameter to docstring

paulromano/openmc,johnnyliu27/openmc,walshjon/openmc,shikhar413/openmc,johnnyliu27/openmc,amandalund/openmc,paulromano/openmc,wbinventor/openmc,smharper/openmc,mit-crpg/openmc,paulromano/openmc,walshjon/openmc,shikhar413/openmc,amandalund/openmc,amandalund/openmc,mit-crpg/openmc,wbinventor/openmc,wbinventor/openmc,johnnyliu27/openmc,smharper/openmc,walshjon/openmc,bhermanmit/openmc,paulromano/openmc,shikhar413/openmc,bhermanmit/openmc,amandalund/openmc,wbinventor/openmc,mit-crpg/openmc,smharper/openmc,johnnyliu27/openmc,liangjg/openmc,walshjon/openmc,liangjg/openmc,liangjg/openmc,mit-crpg/openmc,liangjg/openmc,smharper/openmc,shikhar413/openmc