fix logo

Author: mtezzele

README.md

@@ -1,6 +1,6 @@
 <p align="center">
   <a href="http://mathlab.github.io/PyGeM/" target="_blank" >
-    <img alt="Python Geometrical Morphing" src="readme/logo_PyGeM_small.png" width="175" />
+    <img alt="Python Geometrical Morphing" src="docs/source/_static/logo_PyGeM.png" width="200" />
   </a>
 </p>
 <p align="center">