Update web-apis.ipynb

Author: pitmonticone

content/web-apis.ipynb

@@ -570,7 +570,7 @@
    "source": [
     "## After exercises: Saving retrieved data to disk\n",
     "\n",
-    "Usually, we want to save the retrieved data to disk for later use. For example, we might collect data for one year and later analyze it for a longitudal study.\n",
+    "Usually, we want to save the retrieved data to disk for later use. For example, we might collect data for one year and later analyze it for a longitudinal study.\n",
     "\n",
     "To save the retrieved JSON objects to disk, it is practical to use the JSONLINES file format. The JSONLINES format contains a single valid JSON object on each line. This is preferable to saving each object as its own file since we don't, in general, want to end up with excessive amounts of individual files (say, hundreds of thousands or millions).\n",
     "\n",