document return value of networkhashps for getmininginfo RPC endpoint

src/rpc/mining.cpp

@@ -227,10 +227,11 @@ UniValue getmininginfo(const UniValue& params, bool fHelp)
             "  \"currentblockweight\": nnn, (numeric) The last block weight\n"
             "  \"currentblocktx\": nnn,     (numeric) The last block transaction\n"
             "  \"difficulty\": xxx.xxxxx    (numeric) The current difficulty\n"
-            "  \"errors\": \"...\"          (string) Current errors\n"
+            "  \"errors\": \"...\"            (string) Current errors\n"
+            "  \"networkhashps\": nnn,      (numeric) The network hashes per second\n"
             "  \"pooledtx\": n              (numeric) The size of the mem pool\n"
             "  \"testnet\": true|false      (boolean) If using testnet or not\n"
-            "  \"chain\": \"xxxx\",         (string) current network name as defined in BIP70 (main, test, regtest)\n"
+            "  \"chain\": \"xxxx\",           (string) current network name as defined in BIP70 (main, test, regtest)\n"
             "}\n"
             "\nExamples:\n"
             + HelpExampleCli("getmininginfo", "")