fix links

Author: cecilehannay

notebooks/namelist/overview.ipynb

@@ -66,8 +66,7 @@
    "source": [
     "<div class=\"alert alert-info\">\n",
     "\n",
-    "Complete documentation about the namelist variables can be found on the [CESM webpage.]\n",
-    "(https://docs.cesm.ucar.edu/models/cesm2/settings/current/)\n",
+    "Complete documentation about the namelist variables can be found on the [CESM webpage.](https://docs.cesm.ucar.edu/models/cesm2/settings/current/)\n",
     "\n",
     "</div>"
    ]