CW configuration

* updated documentation for the new BPF transmit shaping

fldigi_doxygen/user_src_docs/configCW.txt

@@ -153,6 +153,16 @@ length as the edge timing is increased. This is useful when
 operating QSK and listening between the character elements.</li>
 </ul>
 
+<li>The transmitted signal can be further wave shaped using a "Windowed-sinc"
+bandpass filter.  It is enabled by checking the "BPF transmit audio" check box.
+The bandwidth of the filter can be adjusted from 10 to 1000 Hertz with the BPF bw
+control.  The filter will always be centered on the AFCW injection frequency 
+(waterfall TX cursor position).  You should both visually observe and listen to 
+the resulting CW signal.  The easiest way to do this is to enable the "Send continuously",
+select a test character and then press the TX button on the main dialog.  The
+weight, dash/dot, edge shape selection, edge timing, BPF and bandwidth can be 
+changed with immediate effect.
+
 This is what the A2 signal should look like with various settings of
 weight, Dash/Dot and Edge. The audio frequency is 400 Hz and
 the TxWPM is 100 WPM.