add other data structures that are supported

ch3/jupyter-notebooks/data_classes.ipynb

@@ -16,6 +16,8 @@
     "\n",
     "* Haystack StreaminhChunk data class \n",
     "\n",
+    "It also provides support for dataframe objects as well as dictionaries and JSON objects. \n",
+    "\n",
     "![](./images/data-structures.png)\n",
     "\n",
     "Each of these classes act as data structures that can be used to store and process data. We can use these classes to store data in a standardized format, and then use the Haystack API to process the data through data pipelines.\n",
@@ -97,7 +99,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "We see that an id was automatically generated for the document. Let's create a dataframe-based document."
+    "We see that an id was automatically generated for the document. Let's access the content and metadata."
    ]
   },
   {