Fix dynamic array spec

Author: supermassive

docs/abi-spec.rst

@@ -191,7 +191,7 @@ on the type of ``X`` being
 
 - ``T[]`` where ``X`` has ``k`` elements (``k`` is assumed to be of type ``uint256``):
 
-  ``enc(X) = enc(k) enc([X[0], ..., X[k-1]])``
+  ``enc(X) = enc(k) enc(([X[0], ..., X[k-1]]))``
 
   i.e. it is encoded as if it were an array of static size ``k``, prefixed with
   the number of elements.