update changes.html

Installation/changes.html

@@ -175,6 +175,8 @@ and <code>src/</code> directories).
       Add some new features to <code>CGAL::isotropic_remeshing()</code>.
       It is now possible to select fixed vertices that survive the remeshing process,
       and to keep face attributes such as colors valid after remeshing.
+      The user can choose the number of relaxation steps happening at each loop,
+      and to run 1-dimensional relaxation along constrained polylines.
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