It is possible to attach the text field in the Documentation tab. However, you will need to add some more scripting in the Process tab of your Standard Notification Object as shown below:
!The following lines will process and get all the lines from the Documentation tab.
:SET &HND# = PREP_PROCESS_DOCU(&$NAME#,Docu)
:PROCESS &HND#
:SET &NEW_LINE# = GET_PROCESS_LINE(&HND#)
:PRINT &NEW_LINE#
!:SET &LINE# = STR_CAT(&LINE#,&NEW_LINE# )
:ENDPROCESS
!The following lines will get the last RunId of the Notification object and put it in the"Attach reports from Task(RunId)" of the Notification Tab
:SET &runid# = GET_UC_OBJECT_NR(<Put your mail object name here>)
:PUT_ATT ATTACH_REPORTS_RUNID =&runid#