Colab tutorials (#367)

* Colab Button & Run added

tutorials/tutorial11/tutorial.ipynb

@@ -6,6 +6,7 @@
    "source": [
     "# Tutorial: PINA and PyTorch Lightning, training tips and visualizations \n",
     "\n",
+    "[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/mathLab/PINA/blob/master/tutorials/tutorial11/tutorial.ipynb)\n",
     "\n",
     "In this tutorial, we will delve deeper into the functionality of the `Trainer` class, which serves as the cornerstone for training **PINA** [Solvers](https://mathlab.github.io/PINA/_rst/_code.html#solvers). \n",
     "\n",
@@ -22,6 +23,15 @@
    "metadata": {},
    "outputs": [],
    "source": [
+    "## routine needed to run the notebook on Google Colab\n",
+    "try:\n",
+    "  import google.colab\n",
+    "  IN_COLAB = True\n",
+    "except:\n",
+    "  IN_COLAB = False\n",
+    "if IN_COLAB:\n",
+    "  !pip install \"pina-mathlab\"\n",
+    "\n",
     "import torch\n",
     "\n",
     "from pina import Condition, Trainer\n",