Documentation for charges and customers lists

**1. Description of change**

Added 2 documentation articles: one for charge list and one for customer list.

**2. Objective reason**

Having an up to date documentation!

**3. Developers affected by the change**

All those who will enjoy the unique pleasures and feeling of accomplishment given by our magnificent API

**4. Impact of the change**

Happy developers who can list charges and customers

**5. Priority of change**

Medium-rare

**6. Alternate solution (if any)**

Pas vraiment.