Fix errors in cn. (#155)

Author: StepfenShawn

cn/examples/section_2/operator.md

@@ -82,9 +82,9 @@ hello world
 
 ## 按位运算符
 
-- `>>`左位移
+- `<<`左位移
 
-- `<<`右位移
+- `>>`右位移
 
 - `&amp;`按位和
 

cn/examples/section_4/array-functions.md

@@ -26,7 +26,7 @@ array.delete(ix type)
 删除索引`ix`处数组中的元素。
 
 ```go
-mut even_numbers = [2, 4, 6, 8, 10]
+mut even_numbers := [2, 4, 6, 8, 10]
 even_numbers.delete(3)
 println(even_numbers) // [2, 4, 6, 10]
 ```