Updated troubleshooting documentation to reflect the new error message for the invalid L(I) usage.
Updated troubleshooting documentation to reflect the new error message for the invalid L(I) usage.

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