Document URI TestSource support of dynamic tests in User Guide

[marcphilipp]

When URI TestSource support for dynamic tests was extended in #1895, we noticed that we don't have any documentation for this feature in the User Guide.

Deliverables

• Add a subsection that documents the different supported URI formats with examples

[ielatif]

@marcphilipp as discussed in #1895 I will add the documentation for 5.5 GA

[marcphilipp]

Great! Feel free to start working on it. If we can get it into 5.5 RC1 that would be even better. 🙂