Updated missing refactor in docs "return_map_steps" (#2956) (#3469)

Minor rename in the documentation that was overlooked when refactoring.

---------

Co-authored-by: Ehmad Zubair <ehmad@cogentlabs.co>

docs/modules/chains/index_examples/qa_with_sources.ipynb

@@ -267,7 +267,7 @@
    "source": [
     "**Intermediate Steps**\n",
     "\n",
-    "We can also return the intermediate steps for `map_reduce` chains, should we want to inspect them. This is done with the `return_map_steps` variable."
+    "We can also return the intermediate steps for `map_reduce` chains, should we want to inspect them. This is done with the `return_intermediate_steps` variable."
    ]
   },
   {