Fix parsing.ipynb to not mention SCOs "inside" observed-data

SDOs anymore.  That is no longer the case in STIX 2.1.

Author: chisholm

docs/guide/parsing.ipynb

@@ -64,7 +64,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Parsing STIX content is as easy as calling the [parse()](../api/stix2.parsing.rst#stix2.parsing.parse) function on a JSON string, dictionary, or file-like object. It will automatically determine the type of the object. The STIX objects within `bundle` objects, and any cyber observables contained within `observed-data` objects will be parsed as well.\n",
+    "Parsing STIX content is as easy as calling the [parse()](../api/stix2.parsing.rst#stix2.parsing.parse) function on a JSON string, dictionary, or file-like object. It will automatically determine the type of the object. The STIX objects within `bundle` objects will be parsed as well.\n",
     "\n",
     "**Parsing a string**"
    ]