Fix a dead URL in perpendicular-flap README.md

Author: MakisH

perpendicular-flap/README.md

@@ -47,7 +47,7 @@ Solid participant:
 
 * Nutils. The structural model is currently limited to linear elasticity. For more information, have a look at the [Nutils adapter documentation](https://precice.org/adapter-nutils.html). This Nutils solver requires at least Nutils v8.0.
 
-* solids4foam. Like for CalculiX, the geometrically non-linear solver is used by default. For more information, see the [solids4foam documentation](https://solids4foam.github.io/documentation/overview.html) and a [related tutorial](https://solids4foam.github.io/tutorials/more-tutorials/flexibleOversetCylinder.html). This case works with solids4foam v2.0, which is compatible with up to OpenFOAM v2012 and OpenFOAM 9 (as well as foam-extend, with which the OpenFOAM-preCICE adapter is not compatible), as well as the OpenFOAM-preCICE adapter v1.2.0 or later.
+* solids4foam. Like for CalculiX, the geometrically non-linear solver is used by default. For more information, see the [solids4foam documentation](https://solids4foam.github.io/documentation/overview.html) and a [related tutorial](https://www.solids4foam.com/tutorials/more-tutorials/fluid-solid-interaction/flexibleOversetCylinder.html). This case works with solids4foam v2.0, which is compatible with up to OpenFOAM v2012 and OpenFOAM 9 (as well as foam-extend, with which the OpenFOAM-preCICE adapter is not compatible), as well as the OpenFOAM-preCICE adapter v1.2.0 or later.
 
 * OpenFOAM (solidDisplacementFoam). For more information, have a look at the [OpenFOAM plateHole tutorial](https://www.openfoam.com/documentation/tutorial-guide/5-stress-analysis/5.1-stress-analysis-of-a-plate-with-a-hole). The solidDisplacementFoam solver only supports linear geometry and this case is only provided for quick testing purposes, leading to outlier results. For general solid mechanics procedures in OpenFOAM, see solids4foam.