[PL/Out] Fix doxygen.

Documentation/ProjectFile/prj/time_loop/output/t_output_extrapolation_residuals.md

-\ogs_missing_documentation
+Output the residuals.

Documentation/ProjectFile/prj/time_loop/processes/process/t_output.md

+Deprecated config tag. Don't use the tag. Please configure your output within
+the global output section, i. e., within the xpath
+'//OpenGeoSysProject/time_loop/output'.

ProcessLib/CreateProcessData.cpp

@@ -81,6 +81,7 @@ std::vector<std::unique_ptr<ProcessData>> createPerProcessData(
             //! \ogs_file_param{prj__time_loop__processes__process__convergence_criterion}
             pcs_config.getConfigSubtree("convergence_criterion"));
 
+        //! \ogs_file_param{prj__time_loop__processes__process__output}
         auto output = pcs_config.getConfigSubtreeOptional("output");
         if (output)
         {

ProcessLib/Output/CreateOutput.cpp

@@ -96,8 +96,8 @@ std::unique_ptr<Output> createOutput(
         output_variables.insert(out_var);
     }
 
+    //! \ogs_file_param{prj__time_loop__output__output_extrapolation_residuals}
     bool const output_residuals = config.getConfigParameter<bool>(
-        //! \ogs_file_param{prj__time_loop__output__output_extrapolation_residuals}
         "output_extrapolation_residuals", false);
 
     ProcessOutput process_output{output_variables, output_residuals};