Updated users guide for kappa-fission tally.
Updated users guide for kappa-fission tally.

nhorelik/openmc,liangjg/openmc,amandalund/openmc,lilulu/openmc,mit-crpg/openmc,johnnyliu27/openmc,nhorelik/openmc,lilulu/openmc,smharper/openmc,paulromano/openmc,kellyrowland/openmc,keadyk/openmc_mg_prepush,amandalund/openmc,walshjon/openmc,bhermanmit/openmc,keadyk/openmc_mg_prepush,smharper/openmc,shenqicang/openmc,johnnyliu27/openmc,walshjon/openmc,amandalund/openmc,bhermanmit/openmc,wbinventor/openmc,wbinventor/openmc,liangjg/openmc,shikhar413/openmc,shenqicang/openmc,johnnyliu27/openmc,bhermanmit/cdash,kellyrowland/openmc,paulromano/openmc,walshjon/openmc,wbinventor/openmc,lilulu/openmc,amandalund/openmc,mit-crpg/openmc,shikhar413/openmc,sxds/opemmc,wbinventor/openmc,liangjg/openmc,mjlong/openmc,keadyk/openmc_mg_prepush,liangjg/openmc,smharper/openmc,paulromano/openmc,mit-crpg/openmc,sxds/opemmc,johnnyliu27/openmc,shikhar413/openmc,walshjon/openmc,samuelshaner/openmc,samuelshaner/openmc,shikhar413/openmc,paulromano/openmc,smharper/openmc,mjlong/openmc,mit-crpg/openmc,samuelshaner/openmc,samuelshaner/openmc