docs: Remove an outdated reference to Serenity

Author: cameel

docs/contracts/events.rst

@@ -15,7 +15,7 @@ arguments to be stored in the transaction's log - a special data structure
 in the blockchain. These logs are associated with the address of the contract that emitted them,
 are incorporated into the blockchain, and stay there as long as a block is
 accessible (forever as of now, but this might
-change with Serenity). The Log and its event data is not accessible from within
+change in the future). The Log and its event data is not accessible from within
 contracts (not even from the contract that created them).
 
 It is possible to request a Merkle proof for logs, so if