README MUI logo (#12273)

The logo is broken at https://www.npmjs.com/package/@material-ui/core because it uses a relative path.
I suggest using an absolute path, and the SVG version at material-ui.com looks better to me

README.md

@@ -1,5 +1,5 @@
 <p align="center">
-  <a href="https://material-ui.com/" rel="noopener" target="_blank"><img width="200" src="/static/brand.png" alt="Material-UI logo"></a></p>
+  <a href="https://material-ui.com/" rel="noopener" target="_blank"><img width="150" src="https://material-ui.com/static/images/material-ui-logo.svg" alt="Material-UI logo"></a></p>
 </p>
 
 <h1 align="center">Material-UI</h1>