doc: remove misleading AreInputsStandard() comment

This check isn't any longer just about bad pay-to-script-hash inputs; it
also excludes any kind of nonstandard input, unknown witness versions,
coinbases, etc.

src/validation.cpp

@@ -814,7 +814,6 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
         return false; // state filled in by CheckTxInputs
     }
 
-    // Check for non-standard pay-to-script-hash in inputs
     if (fRequireStandard && !AreInputsStandard(tx, m_view)) {
         return state.Invalid(TxValidationResult::TX_INPUTS_NOT_STANDARD, "bad-txns-nonstandard-inputs");
     }