edit README

Author: joel-ling

README.md

@@ -271,8 +271,10 @@ type RFC791InternetHeaderFormatWord0 struct {
 }
 ```
 
-As of Version 1.0.0, supported field types are
+As of Version 1, supported field types are
 `uint`, `uint8` a.k.a. `byte`, `uint16`, `uint32`, `uint64` and `bool`.
+[Defined types](https://go.dev/ref/spec#Type_definitions)
+having the above underlying types are compatible.
 
 ##### Offset
 `<offset>` is an integer