Manual: add note about required Octave version under Windows and macOS

doc/manual/source/installation-and-configuration.rst

@@ -15,7 +15,10 @@ are necessary in that case.
 In order to run Dynare, you need one of the following:
 
 * MATLAB version 7.9 (R2009b) or above;
-* Octave version 4.2.1 or above, with the statistics package from `Octave-Forge`_.
+* Octave version 4.2.1 or above, with the statistics package from
+  `Octave-Forge`_. Note however that the Dynare installers for Windows and
+  macOS require a more specific version of Octave, as indicated on the download
+  page.
 
 The following optional extensions are also useful to benefit from
 extra features, but are in no way required: