Correct MySQL Shell/Client section (#12987)

[ti-chi-bot]

This is an automated cherry-pick of #12987

Signed-off-by: Aolin aolin.zhang@pingcap.com

What is changed, added or deleted? (Required)

There are two official command-line clients for MySQL, both open-source and released by the Oracle MySQL team.

1. MySQL Client (mysql), which is part of the MySQL Server code base, but can be installed separately via yum install mysql on most YUM based linux distributions. With the offical YUM repo this becomes yum install mysql-community-client. This client is written in C and has existed for as long as MySQL does.

2. MySQL Shell (mysqlsh), which is a separate code base and can be installed separately. This is a newer tool and supports SQL, but also JS and Python. It has a more modern code base and is more extendable than the 'old' client.

It looks like these two were mixed up into a single section of the docs.

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

• This PR is translated from: Correct MySQL Shell/Client section docs#8779
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• Delete files
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• Might cause conflicts after applied to another branch

[ti-chi-bot]

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[Oreoxmt]

/merge

[ti-chi-bot]

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

Commit hash: ab9e489

[TomShawn]

/verify

[Oreoxmt]

/verify