Include remarks from review

Point_set_processing_3/doc/Point_set_processing_3/NamedParameters.txt

@@ -60,6 +60,8 @@ No default value.
 
 \cgalNPBegin{callback} \anchor PSP_callback
 is a mechanism to get feedback on the advancement of the algorithm while it's running and to interrupt it if needed. It is called regularly when the algorithm is running: the current advancement (between 0. and 1.) is passed as parameter. If it returns `true`, then the algorithm continues its execution normally; if it returns `false`, the algorithm is stopped.\n
+The callback will be copied and therefore needs to be lightweight.\n
+Note that when a callback is run on a parallelized algorithm with `CGAL::Parallel_tag`, it is called asynchronously on a separate thread and should then be thread-safe.\n
 \b Type: `CGAL::cpp11::function<bool(double)>`.\n
 \b Default: empty function.\n
 \cgalNPEnd

Point_set_processing_3/doc/Point_set_processing_3/Point_set_processing_3.txt

@@ -640,7 +640,15 @@ Algorithms that support this mechanism are detailed in the [Reference Manual](@r
 
 \subsection Point_set_processing_3Example_callbacks Example
 
-The following example defines a callback that displays the name of the current algorithm along with the progress (as a percentage) updated every \f$1/10th\f$ of a second.
+The following example defines a callback that displays the name of the current algorithm along with the progress (as a percentage) updated every \f$1/10th\f$ of a second. While the algorithm is running, the console output will typically look like this:
+
+\code{.sh}
+Computing average spacing: 100%
+Grid simplification: 100%
+Jet smoothing: 54%
+\endcode
+
+Thanks to the carriage return character `\r`, the lines are overwritten and the user sees the percentage increasing on each line.
 
 \cgalExample{Point_set_processing_3/callback_example.cpp}
 

Point_set_processing_3/include/CGAL/grid_simplify_point_set.h

@@ -195,7 +195,7 @@ public:
       1.) is passed as parameter. If it returns `true`, then the
       algorithm continues its execution normally; if it returns
       `false`, the algorithm is stopped and simplification stops with
-      no guarantee on the outut.\cgalParamEnd
+      no guarantee on the output.\cgalParamEnd
      \cgalParamBegin{geom_traits} an instance of a geometric traits class, model of `Kernel`\cgalParamEnd
    \cgalNamedParamsEnd
 

Point_set_processing_3/include/CGAL/hierarchy_simplify_point_set.h

@@ -149,7 +149,7 @@ namespace CGAL {
        1.) is passed as parameter. If it returns `true`, then the
        algorithm continues its execution normally; if it returns
        `false`, the algorithm is stopped and simplification stops with
-       no guarantee on the outut.\cgalParamEnd
+       no guarantee on the output.\cgalParamEnd
        \cgalParamBegin{geom_traits} an instance of a geometric traits class, model of `Kernel`\cgalParamEnd
      \cgalNamedParamsEnd