[Doc] added input file docu

Documentation/ProjectFile/prj/processes/process/jacobian_assembler/CompareJacobians/c_CompareJacobians.md

+A Jacobian assembler that assembles the Jacobian in two different ways, compares
+the resulting local Jacobians and writes extensive logs in the form of a Python
+script if the provided tolerances are exceeded.
+
+Logging (and optionally program termination) is triggered only if both the
+absolute and the relative tolerance are exceeded.

Documentation/ProjectFile/prj/processes/process/jacobian_assembler/CompareJacobians/t_abs_tol.md

+The absolute tolerance (component-wise) for the difference between the two
+assembled local Jacobians.
+
+There is only one absolute tolerance value for all components of the Jacobian.

Documentation/ProjectFile/prj/processes/process/jacobian_assembler/CompareJacobians/t_fail_on_error.md

+Whether OGS should be aborted if both the absolute and relative tolerance are
+exceeded.

Documentation/ProjectFile/prj/processes/process/jacobian_assembler/CompareJacobians/t_jacobian_assembler.md

+The Jacobian assember whose assembled matrices will be used subsequently in the
+global equation system.

Documentation/ProjectFile/prj/processes/process/jacobian_assembler/CompareJacobians/t_log_file.md

+The path to the file to which details of differing Jacobians are written.
+
+Finally, the file will contain a Python script that can be used to conveniently
+examine the differences that occured.
+The given path is an absolute path or a path relative to the working directory
+of OGS.
+The log file will be overwritten, even if no differences exceeding the
+tolerances occur.

Documentation/ProjectFile/prj/processes/process/jacobian_assembler/CompareJacobians/t_reference_jacobian_assembler.md

+The Jacobian assembler whose results are used only to check the assembled
+matrices of the other Jacobian assembler.

Documentation/ProjectFile/prj/processes/process/jacobian_assembler/CompareJacobians/t_rel_tol.md

+The relative tolerance (component-wise) for the difference between the two
+assembled local Jacobians.
+
+There is only one relative tolerance value for all components of the Jacobian.