Add perpendicular-flap-stress tutorial to sidebar (#518)

Author: MakisH

_config.yml

@@ -285,6 +285,7 @@ subprojects:
   - imported/tutorials/oscillator
   - imported/tutorials/oscillator-overlap
   - imported/tutorials/perpendicular-flap
+  - imported/tutorials/perpendicular-flap-stress
   - imported/tutorials/turek-hron-fsi3
   - imported/tutorials/partitioned-pipe
   - imported/tutorials/partitioned-pipe-two-phase

_data/sidebars/tutorial_sidebar.yml

@@ -160,9 +160,17 @@ entries:
           url: /tutorials-partitioned-heat-conduction-overlap.html
           output: web
 
-    - title: Perpendicular flap
-      url: /tutorials-perpendicular-flap.html
-      output: web
+      - title: Perpendicular flap
+        output: web
+        subfolderitems:
+
+        - title: Basic variant
+          url: /tutorials-perpendicular-flap.html
+          output: web
+        
+        - title: Stress variant
+          url: /tutorials-perpendicular-flap-stress.html
+          output: web
 
     - title: Resonant circuit
       url: /tutorials-resonant-circuit.html

pages/tutorials/tutorials.md

@@ -64,7 +64,9 @@ In the following cases, you can explore different aspects of preCICE:
   - [Complex variant](tutorials-partitioned-heat-conduction-complex.html): A partitioned heat conduction case with FEniCS, showcasing advanced features and geometries.
   - [Direct mesh access variant](tutorials-partitioned-heat-conduction-direct.html): A partitioned heat conduction case with Nutils, showcasing the direct mesh access feature.
   - [Overlapping Schwarz variant](tutorials-partitioned-heat-conduction-overlap.html): An overlapping Schwarz method of the partitioned heat conduction case, coupling two Dirichlet participants.
-- [Perpendicular flap](tutorials-perpendicular-flap.html) (as in "featured")
+- Perpendicular flap collection
+  - [Basic variant](tutorials-perpendicular-flap.html) (as in "featured")
+  - [Stress variant](tutorials-perpendicular-flap-stress.html)
 - [Resonant circuit](tutorials-resonant-circuit.html): The basic LC circuit, with two MATLAB solvers.
 - [Two-scale heat conduction](tutorials-two-scale-heat-conduction.html): A heat conduction scenario with an underlying micro-structure which is resolved to get the constitutive properties on the macro scale.
 - [Turek-Hron FSI3](tutorials-turek-hron-fsi3.html): The well-known fluid-structure interaction benchmark, with OpenFOAM and deal.II.