Add an information to distinguish sections in the Administration tab

Here are the steps to observe the problem:

1. Create several domains
2. Navigate to a workspace
3. Choose Administration > Publication tab
4. the dropdown list displays items whose each name is "Sections", without any capabilities to distinguish them

To fix the problem, we should list in the selection component the domains, not the sectionsRoot kind of document, even if below, in the tree, we set the sectionRoot as the root of the tree.