Update readme.md

helpers/readme.md

@@ -2,3 +2,5 @@ This custom VonMises distribution is necessary,
 because the default PYMC3 implementation generates samples out of the range of [-pi, pi]. 
 
 Therefore, I adapted the .random() method to map the samples to the correct interval. 
+
+Besides this, the code is directly taken from the [PYMC3](https://github.com/pymc-devs/pymc3) without further changes.