Doc index: modified link to CHM documentation

Author: PierreRaybaut

doc/index.rst

@@ -1,17 +1,19 @@
 .. automodule:: qwt
 
-.. note::
+.. only:: html and not htmlhelp
 
-    Download :download:`CHM Manual <../PythonQwt.chm.zip>`.
+	.. note::
 
-    After downloading this file, you may see blank pages in the documentation. 
-    That's because Windows is blocking CHM files for security reasons. 
-    Fixing this problem is easy:
+		Windows users may download the :download:`CHM Manual <../PythonQwt.chm.zip>`.
 
-        * Right-click the CHM file, select properties, then click “Unblock”.
-        * Or compress the CHM file into a zip archive and decompress it in 
-          another directory.
-        * Do not open the CHM file on a network drive.
+		After downloading this file, you may see blank pages in the documentation. 
+		That's because Windows is blocking CHM files for security reasons. 
+		Fixing this problem is easy:
+
+			* Right-click the CHM file, select properties, then click “Unblock”.
+			* Or compress the CHM file into a zip archive and decompress it in 
+			  another directory.
+			* Do not open the CHM file on a network drive.
 
 Contents: