ticdc-open-api: add an file about ticdc open api

[asddongmen]

What is changed, added or deleted? (Required)

Add docs about the new Open APIs of TiCDC.

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

Tips for choosing the affected version(s):

By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.

For details, see tips for choosing the affected versions (in Chinese).

• master (the latest development version)
• v5.1 (TiDB 5.1 versions)
• 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):
  This PR is migrated from ticdc: add docs about ticdc open api #6834 .

Develop openapi for ticdc. #2411

*: add some open API to cdc. #2416

http_*: add create and update changefeed API #2472

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-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• TomShawn
• hi-rustin

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[TomShawn]

@asddongmen Please add the metadata part and TOC like other documents.

[sunzhaoyang]

rest LGTM

[Rustin170506]

https://docs.github.com/cn/rest/reference/repos

我们在参数说明和内容组织上可不可以参考一下 GitHub API 的文档？

是不是可以把这些 API 按照资源分类加个目录在最前面？

[zier-one]

LGTM

[Rustin170506]

除了 capture 的中文名字，其他的 LGTM。:thumbsup:

[TomShawn]

LGTM

[TomShawn]

/merge

[ti-chi-bot]

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

Commit hash: 06527c9

[TomShawn]

Fixed in #6881.