Update src/Setup_geometry.jl

Co-authored-by: Albert de Montserrat <58044444+albert-de-montserrat@users.noreply.github.com>

Author: boriskaus

src/Setup_geometry.jl

@@ -622,7 +622,7 @@ end
 
 
 """
-        add_polygon!(Phase, Temp, Grid::AbstractGeneralGrid; xlim=(), ylim::Tuple = (0,0.8), zlim=(), phase = ConstantPhase(1), T=nothing, cell=false )   
+        add_polygon!(Phase, Temp, Grid::AbstractGeneralGrid; xlim=(), ylim::Tuple = (0.0,0.8), zlim=(), phase = ConstantPhase(1), T=nothing, cell=false )   
 
 
 Adds a polygon with phase & temperature structure to a 3D model setup.  This simplifies creating model geometries in geodynamic models