[TD-2598] feature: C# taosdemo

update README.md

tests/examples/C#/taosdemo/README.md

@@ -8,4 +8,30 @@ mcs -out:taosdemo *.cs
 
 run C# version taosdemo
 ===
-mono taosdemo [OPTION..]
+Usage: mono taosdemo.exe [OPTION...]
+
+        -h                host, The host to connect to TDengine. Default is localhost.
+        -p                port, The TCP/IP port number to use for the connection. Default is 0.
+        -u                user, The user name to use when connecting to the server. Default is 'root'.
+        -P                password, The password to use when connecting to the server. Default is 'taosdata'.
+        -d                database, Destination database. Default is 'test'.
+        -a                replica, Set the replica parameters of the database, Default 1, min: 1, max: 3.
+        -m                table_prefix, Table prefix name. Default is 't'.
+        -s                sql file, The select sql file.
+        -M                stable, Use super table.
+        -o                outputfile, Direct output to the named file. Default is './output.txt'.
+        -q                query_mode, Query mode--0: SYNC, 1: ASYNC. Default is SYNC.
+        -b                type_of_cols, data_type of columns: 'INT', 'TINYINT', 'SMALLINT', 'BIGINT', 'FLOAT', 'DOUBLE', 'BINARY'. Default is 'INT'.
+        -w                length_of_binary, The length of data_type 'BINARY'. Only applicable when type of cols is 'BINARY'. Default is 8
+        -l                num_of_cols_per_record, The number of columns per record. Default is 3.
+        -T                num_of_threads, The number of threads. Default is 10.
+        -r                num_of_records_per_req, The number of records per request. Default is 1000.
+        -t                num_of_tables, The number of tables. Default is 10000.
+        -n                num_of_records_per_table, The number of records per table. Default is 10000.
+        -c                config_directory, Configuration directory. Default is '/etc/taos/'.
+        -x                flag, Insert only flag.
+        -O                order, Insert mode--0: In order, 1: Out of order. Default is in order.
+        -R                rate, Out of order data's rate--if order=1 Default 10, min: 0, max: 50.
+        -D                Delete data methods 0: don't delete, 1: delete by table, 2: delete by stable, 3: delete by database.
+        -v                Print verbose output
+        -y                Skip read key for continous test, default is not skip