*: update all 5.0-rc descriptions to v5.0 (#5911) (#5923)

[ti-srebot]

cherry-pick #5923 to master
You can switch your code base to this Pull Request by using git-extras:

# In docs-cn repo:
git pr https://github.com/pingcap/docs-cn/pull/5929

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/docs-cn.git pr/5929:master-7101692bac7f

---

cherry-pick #5911 to release-5.0
You can switch your code base to this Pull Request by using git-extras:

# In docs-cn repo:
git pr https://github.com/pingcap/docs-cn/pull/5923

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/docs-cn.git pr/5923:release-5.0-4c276307e79c

---

First-time contributors' checklist

• I've signed Contributor License Agreement that's required for repo owners to accept my contribution.

What is changed, added or deleted? (Required)

After 5.0 GA, we don't need to mention 5.0-rc in our 5.0 GA documentation.

Which TiDB version(s) do your changes apply to? (Required)

• master (the latest development version)
• v5.0 (TiDB 5.0 versions)
• v4.0 (TiDB 4.0 versions)
• v3.1 (TiDB 3.1 versions)
• v3.0 (TiDB 3.0 versions)
• v2.1 (TiDB 2.1 versions)

What is the related PR or file link(s)?

• This PR is translated from:
• Other reference link(s):

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

[ti-srebot]

@ti-srebot you're already a collaborator in bot's repo.

[yikeke]

/merge

[ti-chi-bot]

@yikeke: /merge in this pull request requires 2 /lgtm.

In response to this:

/merge

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[TomShawn]

/lgtm

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• TomShawn
• yikeke

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After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

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[yikeke]

/MERGE

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 2458bde