core: fix comment about recipient for contract creation (#26349)

A comment suggests that contract creation happens if the recipient of a call is 0x00..00 ("zero address") but in fact the sender must be nil. The zero address is a regular valid address that is commonly used as a "burn" address.

core/state_transition.go

@@ -41,7 +41,7 @@ var emptyCodeHash = crypto.Keccak256Hash(nil)
 //
 //  1. Nonce handling
 //  2. Pre pay gas
-//  3. Create a new state object if the recipient is \0*32
+//  3. Create a new state object if the recipient is nil
 //  4. Value transfer
 //
 // == If contract creation ==