Adds coco.fr to the abuse list

[karlcow]

We currently had a series of report for coco.fr which looks like spam.
Let's block them in the meantime.

[karlcow]

https://github.com/webcompat/web-bugs/issues?page=1&q=is%3Aissue+coco+in%3Atitle&utf8=%E2%9C%93

[karlcow]

The storm has passed. Let's close the pull request for now.
#1628

[miketaylr]

It's back. Like 17 in the past few hours.