improve docstrings

Author: ufechner7

src/panel.jl

@@ -26,7 +26,7 @@ Represents a panel in a vortex step method simulation. All points and vectors ar
 - `y_airf::MVec3`: Unit vector parallel to chord line
 - `z_airf::MVec3`: Unit vector in spanwise direction
 - `width::Float64`: Panel width
-- `filaments::Vector{BoundFilament}`: Panel filaments
+- `filaments::Vector{BoundFilament}`: Panel filaments, see: [BoundFilament](@ref)
 """
 mutable struct Panel
     TE_point_1::MVec3

src/solver.jl

@@ -7,10 +7,10 @@ Main solver structure for the Vortex Step Method.
 # Attributes
 
 ## General settings
-- `aerodynamic_model_type`::Symbol
-- density::Float64
+- `aerodynamic_model_type`::Model: The model type, see: [Model](@ref)
+- density::Float64: Air density [kg/m³]
 - `max_iterations`::Int64
-- `allowed_error`::Float64
+- `allowed_error`::Float64: relative error
 - `tol_reference_error`::Float64
 - `relaxation_factor`::Float64