Update README

README.md

@@ -36,7 +36,7 @@ var result = md.render('# Math Rulez! \n  $\\sqrt{3x-1}+(1+x)^2$');
 
 Include the KaTeX stylesheet in your html:
 ```html
-<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.5.1/katex.min.css">
+<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.9.0/katex.min.css">
 ```
 
 If you're using the default markdown-it parser, I also recommend the [github stylesheet](https://github.com/sindresorhus/github-markdown-css):