Allow arbitrary sized msg in signature verification

docs/sophia_stdlib.md

@@ -834,11 +834,14 @@ Hash any object to blake2b
 
 #### verify_sig
 ```
-Crypto.verify_sig(msg : hash, pubkey : address, sig : signature) : bool
+Crypto.verify_sig(msg : bytes(), pubkey : address, sig : signature) : bool
 ```
 
 Checks if the signature of `msg` was made using private key corresponding to
-the `pubkey`
+the `pubkey`.
+
+Note: before v8 of the compiler, `msg` had type `hash` (i.e. `bytes(32)`).
+
 
 #### ecverify_secp256k1
 ```