Fixed typo on CONTRIBUTING

Author: eboadom

CONTRIBUTING.md

@@ -17,5 +17,5 @@ docker-compose up
     PORT - the port for the api, default 3000
     MONGO_URL - mongodb uri, default mongodb://mongodb:27017/aave
     NETWORK - default mainnet
-    JSONRPC_URL - JSON RPC endpoint url to access blokchain data
+    JSONRPC_URL - JSON RPC endpoint url to access blockchain data
     THE_GRAPH_URI - aave v2 compatible thegraph uri