Fix a typo (Monique's suggestion)

Author: lrineau

Installation/CHANGES

@@ -169,7 +169,7 @@ Release date: September 2013
     replaced by a template class Intersection_and_primitive_id<Query> to
     determine the type depending on the query object type.
 
-  - Introduce the class AABB_halfedge_graph_segment_primitive, that replaces
+  - Introduce the class AABB_halfedge_graph_segment_primitive, which replaces
     the class AABB_polyhedron_segment_primitive (which is now deprecated). The
     new class is more general and can be used with any model of HalfedgeGraph.
 

Installation/changes.html

@@ -294,7 +294,7 @@ <h3>3D Fast Intersection and Distance Computation</h3>
       the type depending on the query object type.
     </li>
     <li>Introduce the
-      class <code>AABB_halfedge_graph_segment_primitive</code>, that
+      class <code>AABB_halfedge_graph_segment_primitive</code>, which
       replaces the class <code>AABB_polyhedron_segment_primitive</code>
       (which is now deprecated).  The new class is more general and can be
       used with any model of <code>HalfedgeGraph</code>.</li>