Developer Portal Documentation typo

![image](https://user-images.githubusercontent.com/37819250/62827780-2cfc9d80-bbad-11e9-8eb1-fe5a3bd7aecd.png)
Here,

this "of of". 
![image](https://user-images.githubusercontent.com/37819250/62827782-3be35000-bbad-11e9-9e20-a9ecc34d9c53.png)

You all are amazing, peace!