[tox] Add a dummy test-results.xml file in check-manifest and flake8 environments
This is to work around Jenkins Junit plugin that does not apparently
account for the absence of this file (though it accepts it to be empty).
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/html/index.html
Files: /usr/share/doc/cubicweb-documentation/html/*