fixed broken link to anchor in tutorial

docs/tutorials/grasshopper/beam.rst

@@ -2,10 +2,9 @@
 Beam
 ****
 
-A :code:`Beam` `[source] <https://github.com/gramaziokohler/compas_timber/blob/main/src/compas_timber/parts/beam.py#L47>`__ 
-object represents a linear (straight) timber part with a rectangular cross-section - for example as a stud, rafter, beam, joist etc.
-It has a local coordinate system, where the X-axis corresponds with the *centerline*, 
-Y-axis with the *width* of the cross-section and Z-axis with the *height* of the cross-section. 
+A :class:`~compas_timber.parts.Beam` object represents a linear (straight) timber part with a rectangular cross-section - for example as a stud, rafter, beam, joist etc.
+It has a local coordinate system, where the X-axis corresponds with the *centerline*,
+Y-axis with the *width* of the cross-section and Z-axis with the *height* of the cross-section.
 The *origin* is located at the start of the centerline.
 
 .. image:: ../images/beam_01png.png
@@ -14,18 +13,18 @@ The *origin* is located at the start of the centerline.
 The Grasshopper plugin has two components to create beams:
 
 * 	**BeamFromCurve** - to create a beam form a Grasshopper `Line` or `LineCurve`
-* 	**BeamFromCurveGuid** - to create a beam from a `Guid` of a `Line` object referenced from an active Rhino document. 
-	This one is intended for a design workflow, where the input geometry (centerlines etc.) is drawn or stored in a Rhino document 
-	instead of Grasshopper. 
+* 	**BeamFromCurveGuid** - to create a beam from a `Guid` of a `Line` object referenced from an active Rhino document.
+	This one is intended for a design workflow, where the input geometry (centerlines etc.) is drawn or stored in a Rhino document
+	instead of Grasshopper.
 
 Inputs:
 
 *	`Centerline` : the centerline of the beam, also called the major axis.
-* 	`ZVector`: (optional) a vector used to define the rotation of the cross-section around the centerline. 
-	Together with the centerline it indicates the plane in which the Z-axis of the beam lies, 
-	which is to say that `ZVector` does not have to be perpendicular, but cannot be parallel, to the centerline.  
+* 	`ZVector`: (optional) a vector used to define the rotation of the cross-section around the centerline.
+	Together with the centerline it indicates the plane in which the Z-axis of the beam lies,
+	which is to say that `ZVector` does not have to be perpendicular, but cannot be parallel, to the centerline.
 	If :code:`None` is provided, a default direction will be used:
-    
+
 	* 	vector [1,0,0] (X-direction in world coordinates) if centerline is vertical (parallel to Z-direction in world coordinates)
 	* 	otherwise vector [0,0,1] (Z-direction in world coordinates)