Update README.md

Author: matthiasmullie

README.md

@@ -145,8 +145,3 @@ Although it's recommended to use Composer, you can actually [include these files
 ## License
 
 Minify is [MIT](http://opensource.org/licenses/MIT) licensed.
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-## Challenges
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-If you're interested in learning some of the harder technical challenges I've encountered building this, you probably want to take a look at [what I wrote about it](http://www.mullie.eu/dont-build-your-own-minifier/) on my blog.