added comment

TonioMacaronio · TonioMacaronio · commit b29bdcb87cc1 · 2018-12-14T02:57:40.000+03:00
diff --git a/web3swift/PrecompiledContracts/ERC777/Web3+ERC777.swift b/web3swift/PrecompiledContracts/ERC777/Web3+ERC777.swift
@@ -76,6 +76,7 @@ public class ERC777: IERC777 {
         return ""
     }
     
+    /// Must be 18!
     public var decimals: UInt8 {
         self.readProperties()
         if self._decimals != nil {
