adjust share-related docs

[bachue]

变更背景描述

jira issue链接

主要变更点

• [ ] fix bug
• [ ] new feature
• [ ] 不兼容变更

Checklist

• [ ] 已自测
• [ ] 已更新Readme

[qiniu-prow[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bachue

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/qiniu/qshell/blob/master/OWNERS)~~ [bachue] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment