docs: fix usage in Run pouch command with non-root users

[flyer103]

Ⅰ. Describe what this PR did

Fix usage of Run pouch command with non-root users in INSTALLATION.md.

Ⅱ. Does this pull request fix one issue?

none

Ⅲ. Why don't you add test cases (unit test/integration test)? (你真的觉得不需要加测试吗？)

It only modifies docs.

Ⅳ. Describe how to verify it

In a brand-new linux environment, do as Run pouch command with non-root users in INSTALLATION.md.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request head (doc-fix@4092a31). Click here to learn what that means.
The diff coverage is n/a.

[pouchrobot]

We found this is your first time to contribute to Pouch, @flyer103
👏 We really appreciate it.
Just remind that you have read the contribution guide: https://github.com/alibaba/pouch/blob/master/CONTRIBUTING.md
If you didn't, you should do that first. If done, welcome again and please enjoy hacking! 🍻

[allencloud]

Could you help to take a review for this? Thanks a lot. @Ace-Tang

[fuweid]

@flyer103 please add your sign-off by git commit -s --amend and git push -f origin xxx. Thanks

[fuweid]

sorry to ping @flyer103 you again because the git commit message is not complete. Could you update it?

[flyer103]

@fuweid Done. Sorry for my carelessness.

[Ace-Tang]

LGTM

[fuweid]

the failed case is not caused by this change.
LGTM