fixed comments and the description of the user guide

add the tag-documentation files for the new case

[Test] Reduce number of time steps for decreasing runtime.

Closes #3019

See merge request ogs/ogs!3124

[tests] Testing RemoveGhostData using elliptic square example

See merge request ogs/ogs!3120

[CL] Solution dependent Dirichlet boundary condition

See merge request ogs/ogs!3085

[web] Added note about "Get the source code" for pre-commit installation

See merge request ogs/ogs!3118

LIE extrapolation improvements.

See merge request ogs/ogs!3117

Used in LIE for the stress/strain output, where the fracture
(lower order) elements should not contribute to the extrapolation.

[CMake] Added Apple Clang version check.

See merge request ogs/ogs!3115

Thanks to @KeitaYoshioka for reporting.

[CMake] Enforce conan supplied mfront.

Closes #3034

See merge request ogs/ogs!3113

Fixes #3034.

Thanks to @wenqing for creating the new module.

Pass variables prev to MPL Property::value() calls.

See merge request ogs/ogs!3102

Update exprtk submodule.

Closes #3033

See merge request ogs/ogs!3112

Add extra comment on the misuse of the volumetric strain
for the mechanical volumetric strain.

Using increment version.

Removing misuse of the current state varible transport porosity
as temporary previous state storage.

Now using the previous timestep's values.

With default overload using empty VariableArray for the
previous timestep's values.

Don't misuse current value for porosity in variable_array
for the previous time step value.

Use the new variables array values from previous time step.