docs: Fix comment within "handle long text" example (#21248)

The current doc-string comment is referring to the wrong schema.

docs/docs/use_cases/extraction/how_to/handle_long_text.ipynb

@@ -115,8 +115,8 @@
     "class KeyDevelopment(BaseModel):\n",
     "    \"\"\"Information about a development in the history of cars.\"\"\"\n",
     "\n",
-    "    # ^ Doc-string for the entity Person.\n",
-    "    # This doc-string is sent to the LLM as the description of the schema Person,\n",
+    "    # ^ Doc-string for the entity KeyDevelopment.\n",
+    "    # This doc-string is sent to the LLM as the description of the schema KeyDevelopment,\n",
     "    # and it can help to improve extraction results.\n",
     "    # Note that all fields are required rather than optional!\n",
     "    year: int = Field(\n",