Update _docs_v7/Solver-Setup.md

Co-authored-by: Pedro Gomes <38071223+pcarruscag@users.noreply.github.com>

_docs_v7/Solver-Setup.md

@@ -6,7 +6,7 @@ permalink: /docs_v7/Solver-Setup/
 This is a basic introduction on how to set up a simulation using SU2. We distinguish between single-zone computations and multi-zone computations. The following considers a single zone only. For an explanation on multi-zone problems, continue with [Basics of Multi-Zone Computations](/docs_v7/Multizone).
 
 Three different types of mathematical problems can be solved in SU2. The type of problem to be solved is specified on the config file by the `MATH_PROBLEM` field. The three options are:
-`DIRECT`: also refered to as primal, flow solver.?
+`DIRECT`: Also referred to as primal, this is the default when SU2_CFD or SU2_DEF are used.
 `DISCRETE_ADJOINT`: a discrete adjoint methodology based on Automatic Differentiation.
 `CONTINUOUS_ADJOINT`: a continuous adjoint methodology based on Automatic Differentiation.