Added link to source

Author: sellisd

README.md

@@ -2,6 +2,7 @@
 An [awesome list](https://github.com/sindresorhus/awesome/blob/master/awesome.md) of complex systems science resources.
 
 Website: [https://sellisd.github.io/awesome-complexity/](https://sellisd.github.io/awesome-complexity/)
+Source: [https://github.com/sellisd/awesome-complexity](https://github.com/sellisd/awesome-complexity)
 
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