fix typo

Author: yogo1212

src/flow_control/for.md

@@ -108,7 +108,7 @@ fn main() {
 ```
 
 In the above snippets note the type of `match` branch, that is the key
-difference in the types or iteration. The difference in type then of course
+difference in the types of iteration. The difference in type then of course
 implies differing actions that are able to be performed.
 
 ### See also