clarified NEWS: document_files are officially required since Isabelle2014, but the absence was tolerated as legacy feature;
#hard-wired components
src/Tools/jEdit
src/Tools/Graphview
src/HOL/Mirabelle
src/HOL/Mutabelle
src/HOL/Library/Sum_of_Squares
src/HOL/SPARK
src/HOL/Tools
src/HOL/Tools/ATP
src/HOL/TPTP