[L2-4] Correct small typo

lessons/02_spacetime/02_04_1DBurgers.ipynb

@@ -661,7 +661,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Now, let's create an interactive figure with the `ipywidgets` modules.\n",
+    "Now, let's create an interactive figure with the `ipywidgets` module.\n",
     "We start by importing the module, then define a function (`burgers`) that computes and plots the numerical solution along with the analytical solution, and finally create a interactive widgets (that will call the `burgers` function based on the chosen parameters)."
    ]
   },