message: Doc review: document what is the filtration value when not computed
diff: @@ -259,7 +259,8 @@ class Alpha_complex {
  * `true`.
  * @param[in] exact Exact filtration values computation. Not exact if `Kernel` is not <a target="_blank"
  * href="https://doc.cgal.org/latest/Kernel_d/structCGAL_1_1Epeck__d.html">CGAL::Epeck_d</a>.
  - * @param[in] default_filtration_value Set this value to `true` if filtration values are not needed to be computed.
  + * @param[in] default_filtration_value Set this value to `true` if filtration values are not needed to be computed
  + * (will be set to `NaN`).
  * Default value is `false` (which means compute the filtration values).
  *
  * @return true if creation succeeds, false otherwise.
  