Added note in release notes about confidence intervals.
Added note in release notes about confidence intervals.

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