update readme, add io

cch123 · cch123 · commit 27c9896daec4 · 2021-04-22T16:05:29.000+08:00
diff --git a/readme.md b/readme.md
@@ -29,6 +29,7 @@
 23. [x] [stack dump](runtime_stack.md)
 24. [x] [Atomic](atomic.md)
 25. [ ] [Generics](generics.md)
+26. [x] [IO](io.md)
 
 # Authors
 
