Fix doc issue in summary.rst
Fix doc issue in summary.rst

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