fix coveralls badge

Author: gurneyalex

README.md

@@ -1,6 +1,7 @@
-[![Build Status](https://travis-ci.org/OCA/product-attribute.svg?branch=master)](https://travis-ci.org/OCA/product-attribute)
-[![Coverage Status](https://img.shields.io/coveralls/OCA/product-attribute.svg)](https://coveralls.io/r/OCA/product-attribute?branch=master)
+[![Build Status](https://travis-ci.org/OCA/product-attribute.svg?branch=8.0)](https://travis-ci.org/OCA/product-attribute)
+[![Coverage Status](https://coveralls.io/repos/OCA/product-attribute/badge.png?branch=8.0)](https://coveralls.io/r/OCA/product-attribute?branch=8.0)
 
 Odoo Product Attribute
 ======================
 
+Various addons related to attribute management for products.