Docs change request

[user-name-is-taken]

I didn't see anything in the documents mentioning that every requirement needs to be in a Solved by or Depends on relationship, but when it was the only way I could add my own requirements. It makes since because to require every requirement be connected, but this should be mentioned somewhere a noob can find it, or have a better error message than

+++ ERROR: Problem reading in the continuum [[  69]: Requirements graph has two or more connected components. Please fix the edges between the nodes.Found components: [set([u'project', u'req1']), set([u'flower'])]]
.rmtoo_dependencies:22: recipe for target 'artifacts/reqtopics.tex'failed