ticdc: add three ticdc faqs

[shichun-0415]

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• master (the latest development version)
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What is the related PR or file link(s)?

• This PR is translated from: ticdc: add three ticdc faqs docs-cn#11240
• Other reference link(s):

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• Delete files
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• Might cause conflicts after applied to another branch

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• ran-huang

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[ran-huang]

Rest LGTM

[shichun-0415]

/status LGT2

[shichun-0415]

/merge

[ti-chi-bot]

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

Commit hash: 21288f4

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #10879.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #10880.