Update src/hevm/README.md

Spacing

Co-authored-by: t11s <greenfeatherhelp@gmail.com>

Author: Divide-By-0

src/hevm/README.md

@@ -294,7 +294,7 @@ If you prefer to use your own installation of GHC and the basic Haskell package
 
 **Note:** If you are on macOS when building with Stack, you will first need to install the [secp256k1](https://github.com/bitcoin-core/secp256k1) and [libff](https://github.com/scipr-lab/libff) libraries. These commands should be enough:
 
-	$ brew install automake
+    $ brew install automake
     $ git clone https://github.com/bitcoin-core/secp256k1.git
     $ cd secp256k1
     $ ./autogen.sh