DOC: update CookBook about installation of Python wrappings

Documentation/Cookbook/rst/Installation_Linux.txt

@@ -69,8 +69,10 @@ with ``source otbenv.profile``.
 Python bindings
 ~~~~~~~~~~~~~~~
 
-Starting from OTB 5.8.0, OTB Python bindings are distributed with binary package.
-Currently only Python 2.x is supported and if no compatible Python version is found a
+Starting from OTB 5.8.0, OTB bindings for Python 2.7 are distributed with binary
+package. With OTB 6.4.0, additional bindings for Python 3.5 are also included.
+Please note that using a different Python version may not be compatible with
+OTB wrappings. If no compatible Python 2.x version is found a
 notification is generated during the installation process.  If the installation completes
 without issue, information relating to your Python bindings will be provided. 
 
@@ -78,6 +80,10 @@ You must have Python numpy bindings installed in your system. They can be instal
 without admin rights as follows: "pip install --user numpy". This is to give users the option 
 to select their own existing Python installation rather than the one dibstributed by the OTB package.
 
+By default, bindings for Python 2.7 will be enabled with the ``otbenv`` script.
+If you want to use bindings for Python 3.5, you can copy this script and modify:
+
+- ``lib/python`` into ``lib/python3``, for variable PYTHONPATH
 
 Notes:
 

Documentation/Cookbook/rst/Installation_Macx.txt

@@ -31,14 +31,21 @@ Contents of OTB-|release|-Darwin64 is briefly listed below:
 Python bindings
 ~~~~~~~~~~~~~~~
 
-Starting from OTB 5.8.0, OTB python bindings are distributed with binary package.
-currently only Python 2.x is supported. If no compatible python is found, installation
-notify you about it. If everything works fine, you will be given information about
-using python bindings.
-
-You must have python numpy bindings installed in your system. you can install it locally
-without admin rights with "pip install --user numpy". This is to give users to choose
-their own existing python installation rather than distributing one in OTB package.
+Starting from OTB 5.8.0, OTB bindings for Python 2.7 are distributed with binary
+package. With OTB 6.4.0, additional bindings for Python 3.5 are also included.
+Please note that using a different Python version may not be compatible with
+OTB wrappings. If no compatible Python 2.x version is found a
+notification is generated during the installation process.  If the installation completes
+without issue, information relating to your Python bindings will be provided. 
+
+You must have Python numpy bindings installed in your system. They can be installed locally
+without admin rights as follows: "pip install --user numpy". This is to give users the option 
+to select their own existing Python installation rather than the one dibstributed by the OTB package.
+
+By default, bindings for Python 2.7 will be enabled with the ``otbenv`` script.
+If you want to use bindings for Python 3.5, you can copy this script and modify:
+
+- ``lib/python`` into ``lib/python3``, for variable PYTHONPATH
 
 Notes:
 

Documentation/Cookbook/rst/Installation_Windows.txt

@@ -28,8 +28,10 @@ with ``otbenv.bat``.
 Python bindings
 ~~~~~~~~~~~~~~~
 
-Starting from OTB 5.8.0, OTB Python bindings are distributed with binary package.
-Currently only Python 2.x is supported and if no compatible Python version is found a
+Starting from OTB 5.8.0, OTB bindings for Python 2.7 are distributed with binary
+package. With OTB 6.4.0, additional bindings for Python 3.5 are also included.
+Please note that using a different Python version may not be compatible with
+OTB wrappings. If no compatible Python 2.x version is found a
 notification is generated during the installation process.  If the installation completes
 without issue, information relating to your Python bindings will be provided. 
 
@@ -37,6 +39,11 @@ You must have Python numpy bindings installed in your system. They can be instal
 without admin rights as follows: "pip install --user numpy". This is to give users the option 
 to select their own existing Python installation rather than the one dibstributed by the OTB package.
 
+By default, bindings for Python 2.7 will be enabled with the ``otbenv`` script.
+If you want to use bindings for Python 3.5, you can copy this script and modify:
+
+- ``lib/python`` into ``lib/python3``, for variable PYTHONPATH
+
 Notes
 ~~~~~