Incorrect use of backticks (#8951)

Missing or double backticks corrected.

Found during the overnight documentation build: Doxygen Manual Results
for CGAL-6.1-Ic-182

Author: sloriot

Arrangement_on_surface_2/doc/Arrangement_on_surface_2/CGAL/Arr_observer.h

@@ -3,7 +3,7 @@ namespace CGAL {
 /*! \ingroup PkgArrangementOnSurface2Ref
  *
  * `Arr_observer<Arrangement_2>` is an alias for
- * Aos_observer<Arrangement_on_surface_2>`,
+ * `Aos_observer<Arrangement_on_surface_2>`,
  * where `Arrangement_2` derives from `Arrangement_on_surface_2` and the latter
  * is an instance of the template
  * `CGAL::Arrangement_on_surface_2<GeometryTraits, TopologyTraits>`.

Kinetic_space_partition/doc/Kinetic_space_partition/Concepts/KineticPartitionTraits_3.h

@@ -170,7 +170,7 @@ class KineticSpacePartitionTraits_3 {
 
   /*!
    * Function object type that provides
-   * `Vector_3 operator()(Plane_3 h, Point_3 p)
+   * `Vector_3 operator()(Plane_3 h, Point_3 p)`
    * returns the orthogonal projection of `p` onto `h`.
    */
   typedef unspecified_type Construct_projected_point_3;

Mesh_3/doc/Mesh_3/Mesh_3.txt

@@ -761,7 +761,7 @@ elements) is constructed using a call to the functor `construct_intersection`
 \snippet CGAL/Mesh_3/Construct_initial_points_labeled_image.h use construct intersection
 and eventually `%intersect_index` is the element \#1 of `%intersect`.
 \snippet CGAL/Mesh_3/Construct_initial_points_labeled_image.h get construct intersection
-The dimension of the underlying simplex is stored as the element \#2 of `%intersect``.
+The dimension of the underlying simplex is stored as the element \#2 of `%intersect`.
 
 The result of the custom initialization can be seen in
 \cgalFigureRef{mesh3custominitimage3D}. The generated 3D image contains a

Stream_support/doc/Stream_support/IOstream.txt

@@ -436,7 +436,7 @@ The table above only lists the functions that work with any polygon mesh.
     </tr>
     <tr>
       <td>Output</td>
-      <td>``CGAL::IO::write_polygon_mesh()`</td>
+      <td>`CGAL::IO::write_polygon_mesh()`</td>
       <td>`CGAL::IO::write_OFF()`</td>
       <td>`CGAL::IO::write_STL()`</td>
       <td>`CGAL::IO::write_VTP()`</td>