Add advice on sample rate.

It's good to have the sample rate be an integer multiple or divisor of
the source material's sample rate, or even better, have it be the
same.

README.md

@@ -124,10 +124,11 @@ Setting the sampling rate (optional)
 To satisfy your audiophile feelings, or to reduce unnecessary
 resampling, you might want to set a higher sampling rate and/or
 sampling width. You can do that on the driver "Advanced" property
-page, as shown below. *Warning:* using high sampling freqs with
-24/32 bits width in combination with multichannel can lead to high
-bit rates on the network. We recommend to stick to 48kHz/16 bits
-for 5.1 or higher channel modes.
+page, as shown below. *Warning:* using high sampling freqs with 24/32
+bits width in combination with multichannel can lead to high bit rates
+on the network. We recommend to stick to 48kHz/16 bits for 5.1 or
+higher channel modes, or 44.1kHz/16 if you are going to listen to
+music from CDs.
 
 <img src="doc/sampling-rate.png" alt="Bring up the Speakers Properties window and go to the Advanced tab to set the sample rate."> width="700"/>