Merge branch 'main' into index

Author: jhamman

fundamentals/01_datatree_hierarchical_data.ipynb

@@ -23,7 +23,7 @@
    "metadata": {},
    "source": [
     "\n",
-    "### What is a DataTree\n",
+    "## What is a DataTree\n",
     "\n",
     "### Example DataTree 1\n",
     "\n",