增加 Seek 方法.

Signed-off-by: rick.chan <chenyang@autoai.com>

Software/Development/Language/Go/Basic/Go_文件操作.md

@@ -73,6 +73,18 @@ func (f *File) Read(b []byte) (n int, err error)
 func (f *File) Write(b []byte) (n int, err error)
 ```
 
+### 1.6.设置读写位置
+
+```go
+/**
+ * @param whence
+ *      os.SEEK_SET: seek relative to the origin of the file
+ *      os.SEEK_CUR: seek relative to the current offset
+ *      os.SEEK_END: seek relative to the end
+ */
+func (f *File) Seek(offset int64, whence int) (ret int64, err error)
+```
+
 ## 2.ioutil 包
 
 ### 2.1.读取