rssi doc.

README.md

@@ -76,12 +76,15 @@ For example, make a recording with a sample rate of 20.48e6, for 2 seconds (4096
 $ wget -nv -O- localhost:8000/v1/record/100000000/409600000/20480000
 ```
 
-To stream RSSI values instead, call (note that the duration argument must be present, but is not currently used):
+To stream RSSI values instead, call:
 
 ```
 $ wget -nv -O- localhost:8000/v1/rssi/100000000/409600000/20480000
 ```
 
+If the sample count parameter is 0, the stream will not end
+until a new RPC (whether rssi or record) is received.
+
 ## Working with worker I/Q recordings
 
 Workers make recordings that are compressed with zstandard, and are typically in complex number, int16 format, and include the center frequency and sample rate that the recording was made with. gamutRF tools can generally work with such files directly, but other tools require the recordings to be converted (see below).