Update README.md to fix citation link

Author: samGreer

README.md

@@ -69,5 +69,5 @@ If Matplotlib contributes to a project that leads to publication, please
 acknowledge this by citing Matplotlib.
 
 [A ready-made citation
-entry](https://matplotlib.org/stable/project/citing.html) is
+entry](https://matplotlib.org/stable/users/project/citing.html) is
 available.