update doc

Author: AtsushiSakai

Localization/extended_kalman_filter/extended_kalman_filter_localization.ipynb

@@ -162,7 +162,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "# Observation Model\n",
+    "### Observation Model\n",
     "\n",
     "The robot can get x-y position infomation from GPS.\n",
     "\n",
@@ -204,7 +204,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "# Extented Kalman Filter\n",
+    "### Extented Kalman Filter\n",
     "\n",
     "Localization process using Extendted Kalman Filter:EKF is\n",
     "\n",