Update reference/json-rpc/eth.md

Co-authored-by: longfeiW <[email protected]>

Author: xBalbinus

reference/json-rpc/eth.md

@@ -38,7 +38,7 @@ FilecoinAddressToEthAddress converts any Filecoin address to an EthAddress.
 
 This method supports all Filecoin address types:
 
-- f0 and f4 addresses: Converted directly.
+- `f0` and `f4` addresses: Converted directly.
 - f1/f2/f3 addresses: First converted to their corresponding f0 ID address, then to an EthAddress.
 
 > **Note:**