[MS][MD]Offical website cache tutorial need update.

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Bug Report	Use this template for reporting a bug	kind/bug

Environment

Hardware Environment(Ascend/GPU/CPU):

Uncomment only one /device <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/device cpu

Software Environment:
-- MindSpore version (source or binary): master 2021/8/12 commit_id = ''[sha1]:50d54a74,[branch]:(HEAD->master,origin/master,origin/HEAD)''
-- Python version (e.g., Python 3.7.5): Python3.7.5
-- OS platform and distribution (e.g., Linux Ubuntu 16.04): Ubuntu 18.04
-- GCC/Compiler version (if compiled from source):

Related testcase

test_ms_check_cache_tutorial

Steps to reproduce the issue

check https://mindspore.cn/docs/programming_guide/zh-CN/master/cache.html#%E7%BC%93%E5%AD%98%E6%80%A7%E8%83%BD%E8%B0%83%E4%BC%98

Describe the current behavior

tutorial constraint show MindDataset not support cache.

Describe the expected behavior

MindDataset support cache.

Related log / screenshot

enter image description here

Special notes for this issue

官网cache教程资料描述有误，MindDataset支持cache功能

Please add labels (comp or sig),also you can visit "https://gitee.com/mindspore/community/blob/master/sigs/dx/docs/labels.md" to find more.
为了让问题更快得到响应，请您为该issue打上 组件(comp)或兴趣组(sig) 标签，打上标签的问题可以直接推送给责任人进行处理。更多的标签可以查看
https://gitee.com/mindspore/community/blob/master/sigs/dx/docs/labels.md
以组件问题为例，如果你发现问题是data组件造成的，你可以这样评论：
//comp/data
当然你也可以向data SIG组求助，可以这样写：
//comp/data
//sig/data
如果是一个简单的问题，你可以留给刚进入社区的小伙伴来回答，这时候你可以这样写：
//good-first-issue
恭喜你，你已经学会了使用命令来打标签，接下来就在下面的评论里打上标签吧！

hello, @luopenghui , Has this problem been resolved? If it is in progress, please change the status to WIP. If the issue was solved, please close this issue, thanks!
你好, @luopenghui , 这个问题是否已经解决了呢？如果正在进行中，请把issue状态设置为WIP；如果问题已解决，请关闭这个issue，谢谢！

doc PR: https://gitee.com/mindspore/docs/pulls/5222 has been merged.
But we may need to wait for 1 or 2 more days for the official website to update.

Regression Time ：2021/9/12
Regression Version ：commit_id = ''[sha1]:8a51311e,[branch]:(HEAD,origin/master,origin/HEAD,master)''
Regression Step : check https://mindspore.cn/docs/programming_guide/zh-CN/master/cache.html#%E7%BC%93%E5%AD%98%E6%80%A7%E8%83%BD%E8%B0%83%E4%BC%98
Regression Result : MindDataset not support cache description is delete.
输入图片说明
Regression Conclusion ：Pass

GVP MindSpore / mindspore

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