Update docs/zkEVM/spec/evm-differences.md

Co-authored-by: Dra Murphy <149679879+kmurphypolygon@users.noreply.github.com>

Author: EmpieichO

docs/zkEVM/spec/evm-differences.md

@@ -43,7 +43,7 @@ Below is a list of the changes we have made with Opcodes in zkEVM in comparison
 
    - **SELFDESTRUCT** → removed and replaced by **SENDALL**.
 
-   - **EXTCODEHASH** → returns the hash of the contract bytecode from the zkEVM state tree without checking if the account is empty.
+   - `EXTCODEHASH` returns the hash of the contract bytecode from the zkEVM state tree without checking if the account is empty.
 
    - **DIFFICULTY** →  returns "0" instead of a random number as in the EVM.