update readme in evm-test

evm-tests/README.md

@@ -1,15 +1,30 @@
 # type-test
 
-test with ts
+The evm-tests folder includes all typescript code to test the basic EVM function
+like token transfer, and all precompile contracts in Subtensor. It is
+implemented in typescript, use both ethers and viem lib to interact with
+contracts. The polkadot API is used to call extrinsic, get storage in Subtensor
+. The developers can use it to verify the code change in precompile contracts.
+
+It is also included in the CI process, all test cases are executed for new
+commit. CI flow can get catch any failed test cases. The polkadot API get the
+latest metadata from the runtime, the case also can find out any incompatibility
+between runtime and precompile contracts.
 
 ## polkadot api
 
+To get the metadata, you need start the localnet via run
+`./scripts/localnet.sh`. then run following command to get metadata, a folder
+name .papi will be created, which include the metadata and type definitions.
+
 ```bash
-npx papi add devnet -w ws://10.0.0.11:9944
+npx papi add devnet -w ws://localhost:9944
 ```
 
 ## get the new metadata
 
+If the runtime is upgrade, need to get the metadata again.
+
 ```bash
 sh get-metadata.sh
 ```