bitcoin-cli: Document RBF service bit in "serv" column

Author: luke-jr

src/bitcoin-cli.cpp

@@ -700,6 +700,7 @@ class NetinfoRequestHandler : public BaseRequestHandler
         "           \"c\" - COMPACT_FILTERS: peer can handle basic block filter requests (see BIPs 157 and 158)\n"
         "           \"l\" - NETWORK_LIMITED: peer limited to serving only the last 288 blocks (~2 days)\n"
         "           \"2\" - P2P_V2: peer supports version 2 P2P transport protocol, as defined in BIP 324\n"
+        "           \"r\" - REPLACE_BY_FEE? peer supports replacement of transactions without BIP 125 signalling\n"
         "           \"u\" - UNKNOWN: unrecognized bit flag\n"
         "  v        Version of transport protocol used for the connection\n"
         "  mping    Minimum observed ping time, in milliseconds (ms)\n"