langchain-docs: Correct the word "iteratively" in use-cases documentation (#15697)

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**Description:** Fixes the word "iteratively" in the use-cases
documentation
**Twitter handle:** @untilhamza

docs/docs/use_cases/summarization.ipynb

@@ -409,7 +409,7 @@
     "    llm_chain=reduce_chain, document_variable_name=\"docs\"\n",
     ")\n",
     "\n",
-    "# Combines and iteravely reduces the mapped documents\n",
+    "# Combines and iteratively reduces the mapped documents\n",
     "reduce_documents_chain = ReduceDocumentsChain(\n",
     "    # This is final chain that is called.\n",
     "    combine_documents_chain=combine_documents_chain,\n",