docs: add InitEvmCoinInfo code example to migration guide (cosmos#793)

Author: Cordtus

docs/migrations/v0.4.0_to_v0.5.0.md

@@ -352,8 +352,16 @@ In your UpgradeHandler:
 
 - **If your chain does not have DenomMetadata set for the EVM Denom, you must include it.**
 - **If your chain's EVM denom is *not* 18 decimals, you must add ExtendedDenomOptions to your `x/vm` params.**
+- **After setting metadata, initialize EVM coin info:**
 
-Please refer to the [upgrade example](https://github.com/cosmos/evm/blob/0995962c2fd77a7a23e93001d5a531abbb1b61e5/evmd/upgrades.go) for more information.
+```go
+// After setting denom metadata
+if err := app.EVMKeeper.InitEvmCoinInfo(ctx); err != nil {
+    return nil, err
+}
+```
+
+Please refer to the [upgrade example](https://github.com/cosmos/evm/blob/main/evmd/upgrades.go) for the complete implementation.
 
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