Update forward.md

Author: schoffelen

development/module/forward.md

@@ -116,7 +116,7 @@ Detailed information for each of the functions that creates a head model can be
 - **[ft_headmodel_singleshell](/reference/forward/ft_headmodel_singleshell)**
 - **[ft_headmodel_singlesphere](/reference/forward/ft_headmodel_singlesphere)**
 
-An important prerequisite for correct forward computations, is that the geometrical information in the relevant data objects is comparable, i.e. that they are coregistered with respect to one another, and that the metric units, and the coordinate systems in which the spatial coordinates are expressed are the same. If needed, the units and coordinate system of data objects containing geometrical information can be explored using **[ft_determine_units](/reference/forward/ft_determine_units)** and **[ft_determine_coordsys](/reference/forward/ft_determine_coordsys)**. These functions require visualization functions from the [plotting](/development/module/module). If desired, the spatial coordinates of the geometries in the data objects can be manipulated with **[ft_transform_geometry](/reference/utilities/ft_transform_geometry)**, **[ft_convert_units](/reference/forward/ft_convert_units)** and **[ft_convert_coordsys](/reference/utilities/ft_convert_coordsys)**
+An important prerequisite for correct forward computations, is that the geometrical information in the relevant data objects is comparable, i.e. that they are coregistered with respect to one another, and that the metric units, and the coordinate systems in which the spatial coordinates are expressed are the same. If needed, the units and coordinate system of data objects containing geometrical information can be explored using **[ft_determine_units](/reference/forward/ft_determine_units)** and **[ft_determine_coordsys](/reference/forward/ft_determine_coordsys)**. These functions require visualization functions from the [plotting](/development/module/plotting) module. If desired, the spatial coordinates of the geometries in the data objects can be manipulated with **[ft_transform_geometry](/reference/utilities/ft_transform_geometry)**, **[ft_convert_units](/reference/forward/ft_convert_units)** and **[ft_convert_coordsys](/reference/utilities/ft_convert_coordsys)**
 
 Up to here the head model only depends on the geometrical description of the volume conductor and is independent of the data, with exception of the MEG localspheres model. The consequence is that the head model can be used for multiple experimental sessions, multiple electrode or gradiometer placements, or different selections of channels for a single session. The head model, i.e. the `headmodel` structure, can be saved to disk and re-used in an analysis on the next day.