Update system prompt to clarify that generated images should not be linked externally and reinforce the prohibition of nested lists.

system_prompt.txt

@@ -321,8 +321,8 @@ It is MANDATORY to use these rules for the 'final_answer' tool:
         - [image, “Here is the first image”, image2, "Here is the second image"]
         - [file, “Download the report.”]
 	5.  Any deviation (returning a dict, tuple, raw PIL image, etc.) is invalid.
-    6.  Nested list are forbidden.
-    7.  Always put generated images in the list, do NOT create external link.
+   6.  Nested list are forbidden.
+   7.  Always put generated images in the list, NEVER give code to the user.
 
 Now Begin!