Add missing spaces in the strings that are split for line wrapping

module-xrdp-sink.c

@@ -77,7 +77,7 @@ PA_MODULE_USAGE(
         "sink_name=<name for the sink> "
         "sink_properties=<properties for the sink> "
         "format=<sample format> "
-        "rate=<sample rate>"
+        "rate=<sample rate> "
         "channels=<number of channels> "
         "channel_map=<channel map>");