added import missing

tasks/task_05_CSG_cell_tally_TBR/2_example_tritium_production_study.ipynb

@@ -14,14 +14,22 @@
   {
    "cell_type": "markdown",
    "metadata": {},
-   "source": []
+   "source": [
+    "First import OpenMC and configure the nuclear data path"
+   ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {},
    "outputs": [],
-   "source": []
+   "source": [
+    "import openmc\n",
+    "\n",
+    "# Setting the cross section path to the correct location in the docker image.\n",
+    "# If you are running this outside the docker image you will have to change this path to your local cross section path.\n",
+    "openmc.config['cross_sections'] = '/nuclear_data/cross_sections.xml'"
+   ]
   },
   {
    "cell_type": "markdown",