Update README.md

Fix matplotlib Cheatsheets link: https://github.com/matplotlib/cheatsheets
Current link returns a Page not found error.

Author: flegaspi700

3-Data-Visualization/09-visualization-quantities/README.md

@@ -21,7 +21,7 @@ An excellent library to create both simple and sophisticated plots and charts of
 
 If you have a dataset and need to discover how much of a given item is included, one of the first tasks you have at hand will be to inspect its values. 
 
-✅ There are very good 'cheat sheets' available for Matplotlib [here](https://github.com/matplotlib/cheatsheets/blob/master/cheatsheets-1.png) and [here](https://github.com/matplotlib/cheatsheets/blob/master/cheatsheets-2.png).
+✅ There are very good 'cheat sheets' available for Matplotlib [here](https://github.com/matplotlib/cheatsheets).
 
 ## Build a line plot about bird wingspan values