diff --git a/src/chains/README.md b/src/chains/README.md
index fd241dc6..d804dc50 100644
--- a/src/chains/README.md
+++ b/src/chains/README.md
@@ -4,7 +4,7 @@
 
 - Submit configs for mainnet, go to https://github.com/ping-pub/explorer/tree/master/src/chains/mainnet
 
-- Submit configs for testnet, go to https://github.com/ping-pub/explorer/tree/testnet/src/chains/testnet
+- Submit configs for testnet, go to https://github.com/ping-pub/explorer/tree/master/src/chains/testnet
 
 # Sample of Config
 
@@ -12,7 +12,7 @@
 {
     "chain_name": "cosmos",
     "api": ["https://cosmos.api.ping.pub"], 
-    "rpc": ["https://cosmos.rpc.ping.pub:443","http://your-host:26657"]
+    "rpc": ["https://cosmos.rpc.ping.pub:443","http://your-host:26657"],
     "sdk_version": "0.42.6",
     "coin_type": "118",
     "min_tx_fee": "800",
@@ -29,7 +29,7 @@
 ```
 - **chain_name** the name to identify the chain on ping.pub
 - **api** the rest api endpoint.(make sure that CORS is enabled: `Allow-Control-Allow-Origin: *`)
-- **rpc** the rpc endpoint, make sure that the port is added. 
+- **rpc** the rpc endpoint, make sure that the port is added. rpc endpoint is only used for state sync. it's optional.
 - **assets** Native Assets on blockchain. 
 # Test