Update demo_parsing_instructions.ipynb (#86)

usefull -> useful

examples/demo_parsing_instructions.ipynb

@@ -20,7 +20,7 @@
         "# LlamaParse - Parsing comic books with parsing intructions\n",
         "Parsing intructions allow you to instruct our parsing model the same way you would instruct an LLM!\n",
         "\n",
-        "They can be usefull to help the parser get better results on complex document layouts, to extract data in a specific format, or to transform the document in other ways.\n",
+        "They can be useful to help the parser get better results on complex document layouts, to extract data in a specific format, or to transform the document in other ways.\n",
         "\n",
         "Using Parsing Instruction you will get better results out of LlamaParse on complicated documents, and also be able to simplify your application code."
       ],
@@ -612,4 +612,4 @@
       }
     }
   ]
-}
+}