Merge #15790: [0.18] backport #15754

60d4621975 rpc: getrpcinfo docs (Ben Carman)

Pull request description:

  Backports #15754 to the 0.18 branch

  #15754 added the help message for `getrpcinfo`

ACKs for commit 60d462:
  promag:
    utACK 60d4621.
  fanquake:
    utACK 60d4621

Tree-SHA512: 3c0f0aded2dbd300b1cb5e3a3abb1d84852a165aa6ebb337833f06ba135730192a6e86b58323e4c5eb3a7636268125bea7be05925b5b316220bfa5ac1de4a5f4

src/rpc/server.cpp

@@ -296,8 +296,20 @@ static UniValue getrpcinfo(const JSONRPCRequest& request)
             RPCHelpMan{"getrpcinfo",
                 "\nReturns details of the RPC server.\n",
                 {},
-                RPCResults{},
-                RPCExamples{""},
+                RPCResult{
+            "{\n"
+            " \"active_commands\" (array) All active commands\n"
+            "  [\n"
+            "   {               (object) Information about an active command\n"
+            "    \"method\"       (string)  The name of the RPC command \n"
+            "    \"duration\"     (numeric)  The running time in microseconds\n"
+            "   },...\n"
+            "  ]\n"
+            "}\n"
+                },
+                RPCExamples{
+                    HelpExampleCli("getrpcinfo", "")
+                + HelpExampleRpc("getrpcinfo", "")},
             }.ToString()
         );
     }