Please document the required 'qunit' module id

[agistrilink]

In the case of amd loading, the require call uses the 'qunit' module id, i.e. require(['qunit'], factory).

As qunit.js defines itself anonymously, the 'qunit' must be defined and point to the correct qunit.js file. When using requirejs, this means that the 'qunit' should be defined in the paths option of the config.js file.

This external assumption/requirement should be documented.