Merge branch 'feature/examples-rel-paths' into 'master'

[example] Use relative paths for example links on main page

See merge request !1963

examples/README.md

@@ -3,7 +3,7 @@
 To get started with DuMu<sup>x</sup>, we recommend the following documented examples. Each example folder contains a ready-to-use DuMu<sup>x</sup> simulation example.
 The description in each folder (best viewed online by following the link) explains each line of the code example.
 
-### [:open_file_folder: Example 1: One-phase flow and tracer transport](https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/tree/master/examples/1ptracer)
+### [:open_file_folder: Example 1: One-phase flow and tracer transport](1ptracer/README.md)
 
 In this example, we simulate tracer transport through a confined aquifer with a randomly distributed permeability field.
 We first solve the pressure field, compute the steady state flow field, and then solve the tracer transport equation.
@@ -15,7 +15,7 @@ You learn how to
     * compute the flow field from a pressure solution to pass to a tracer problem
     * solve an instationary tracer transport problem with a given flow field
 
-### [:open_file_folder: Example 2: Two-phase flow with infiltration and adaptive grid](https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/tree/master/examples/2pinfiltration)
+### [:open_file_folder: Example 2: Two-phase flow with infiltration and adaptive grid](2pinfiltration/README.md)
 
 In this example we model a soil contamination problem where DNAPL infiltrates a water-saturated porous medium (two-phase flow).
 The initial distribution of DNAPL is read in from a txt-file.
@@ -27,7 +27,7 @@ You learn how to
 * implement a problem with heterogenous material parameters
 * use adaptive grid refinement around the saturation front
 
-### [:open_file_folder: Example 3: Shallow water model](https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/tree/master/examples/shallowwaterfriction)
+### [:open_file_folder: Example 3: Shallow water model](shallowwaterfriction/README.md)
 
 The shallow water flow model is applied to simulate steady subcritical flow in a river including a bottom friction model.
 You learn how to
@@ -35,7 +35,7 @@ You learn how to
 * solve a shallow water flow problem including bottom friction
 * computate and output (VTK) an analytical reference solution
 
-### [:open_file_folder: Example 4: Freeflow channel](https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/tree/master/examples/freeflowchannel)
+### [:open_file_folder: Example 4: Freeflow channel](freeflowchannel/README.md)
 In this example, we simulate a free flow between two plates in two dimensions.
 You learn how to