doc legere modif

README.md

@@ -20,7 +20,12 @@ It is important to note than blocks need preferably be executed from the top dow
 
 ## Visualizing our notebook
 
-The simplest way is to go to the [nbviewer](https://nbviewer.jupyter.org/) website and type `https://signolle.iiens.net/files/heldAndKarp.ipynb`
+The simplest way is to go to the [nbviewer](https://nbviewer.jupyter.org/) website and type 
+
+```
+https://signolle.iiens.net/files/heldAndKarp.ipynb
+```
+
 in the search bar.
 
 ![Screenshot of nbviewer ](images/nbviewer.png)