docs: add a header to all auto converted files

This commits adds the following header to each autoconverted .rst file:

.. ATTENTION do not edit this file manually.
   It was automatically converted from the corresponding .tex file

docs/manuals/en/new_main_reference/post_conversion_changes.sh

@@ -339,6 +339,15 @@ ${PERL} 's#:raw-latex:`\\host\{(.*?)\}`#:strong:`\1`#g' ${DESTFILE}
 
 
 
+# add rst comment that this file was automatically converted
+
+mv  ${DESTFILE}  ${DESTFILE}.tmp
+echo ".. ATTENTION do not edit this file manually." > ${DESTFILE}
+echo "   It was automatically converted from the corresponding .tex file" >> ${DESTFILE}
+echo "" >> ${DESTFILE}
+cat ${DESTFILE}.tmp >> ${DESTFILE}
+rm ${DESTFILE}.tmp
+
 diff  --color -ruN   ${DESTFILE}.bak ${DESTFILE}
 
 exit 0