fix getnettotals RPC description about timemillis.

Author: Masahiko Hyuga

src/rpc/net.cpp

@@ -331,7 +331,7 @@ UniValue getnettotals(const JSONRPCRequest& request)
             "{\n"
             "  \"totalbytesrecv\": n,   (numeric) Total bytes received\n"
             "  \"totalbytessent\": n,   (numeric) Total bytes sent\n"
-            "  \"timemillis\": t,       (numeric) Total cpu time\n"
+            "  \"timemillis\": t,       (numeric) Current UNIX time in milliseconds\n"
             "  \"uploadtarget\":\n"
             "  {\n"
             "    \"timeframe\": n,                         (numeric) Length of the measuring timeframe in seconds\n"