[PL/SourceTerms] Documentation.

Documentation/ProjectFile/prj/process_variables/process_variable/source_terms/i_source_terms.md

+Contains source terms for the process variable.

Documentation/ProjectFile/prj/process_variables/process_variable/source_terms/source_term/Nodal/c_Nodal.md

+Declares a source term to be associated to a node.

Documentation/ProjectFile/prj/process_variables/process_variable/source_terms/source_term/Nodal/t_value.md

+The value for the nodal source term.

Documentation/ProjectFile/prj/process_variables/process_variable/source_terms/source_term/i_source_term.md

+Defines a source term for a process variable.

Documentation/ProjectFile/prj/process_variables/process_variable/source_terms/source_term/t_component.md

+For the multi-component process variables specifies the component of the
+source term. The component ids start with 0. For single-component
+variables this is optional and defaults to 0.

Documentation/ProjectFile/prj/process_variables/process_variable/source_terms/source_term/t_geometrical_set.md

+The name of the geometrical set (see \ref ogs_file_param__gml__name) in which
+the \ref
+ogs_file_param__prj__process_variables__process_variable__source_terms__source_term__geometry
+"geometry" is defined.

Documentation/ProjectFile/prj/process_variables/process_variable/source_terms/source_term/t_geometry.md

+The name of the geometry on which the source term is defined.

Documentation/ProjectFile/prj/process_variables/process_variable/source_terms/source_term/t_type.md

+Sets the type of the source term.