update readme

Signed-off-by: disksing <[email protected]>

Author: disksing

Diff for: README.md

@@ -1,5 +1,7 @@
 # iter
 
+**Note: I'm currently working on making it work with Go generics. For previous version, please check `v1` branch.**
+
 Go implementation of C++ STL iterators and algorithms.
 
 Less hand-written loops, more expressive code.

Diff for: README_ZH.md

@@ -1,5 +1,7 @@
 # iter
 
+**注意：我正在努力使其兼容 Go1.18 支持的泛型。如需旧版本请查看 `v1` 分支。**
+
 C++ STL 迭代器和算法库的 Go 语言实现。
 
 更少的手写循环，更多富有表达力的代码。