Add demo smart contract and ABI JSON files location.
### Compile and Run Demo
#### Ready
SDK provides Demo based on Ethereum, PlatON, PlatONE, FISCO-BCOS, Hyperledger Fabric and HW-BCS. Before running these demos, the corresponding blockchain node software is need to installed(or have known nodes) and deploy the smart contracts required by the demo.
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+The smart contract used by the demo and its ABI JSON file are placed in:
+
+|Demo smart contract |Contract ABI JSON file |use |
+|:----------------------------------------------------------- |:------------------------------------------------------------ |:-------------- |
+|\<SDKRoot\>/demo/demo_ethereum/demo_contract/StoreRead.sol |\<SDKRoot\>/demo/demo_ethereum/demo_contract/StoreRead.json |Ethereum demo |
+|\<SDKRoot\>/demo/demo_platone/demo_contract/StoreRead.sol |\<SDKRoot\>/demo/demo_platone/demo_contract/StoreRead.json |PlatONE demo |
+|\<SDKRoot\>/demo/demo_fiscobcos/demo_contract/HelloWorld.sol |\<SDKRoot\>/demo/demo_fiscobcos/demo_contract/HelloWorld.json |FISCO-BCOS demo |
+
