update dask doc to have info on pyarrow string

docs/source/guides/using_dask_entitysets.ipynb

@@ -248,7 +248,10 @@
     "\n",
     "The use of `featuretools.remove_low_information_features()` cannot currently be used with a Dask feature matrix.\n",
     "\n",
-    "When manually defining a `Feature`, the `use_previous` parameter cannot be used if this feature will be applied to calculate a feature matrix from a Dask `EntitySet`."
+    "When manually defining a `Feature`, the `use_previous` parameter cannot be used if this feature will be applied to calculate a feature matrix from a Dask `EntitySet`.\n",
+    "\n",
+    "### Dask `string[pyarrow]`\n",
+    "Featuretools may have issues with the new string storage model used by Dask.  To workaround this, add `dask.config.set({'dataframe.convert-string': False})`, prior to running dask operations."
    ]
   }
  ],