docs: Update cors.md, Explanation of how routing HTTP method configuration affects browser behavior when the CORS plugin is activated

[cylinder-lee-cn]

对路由中http方法的配置导致cros插件生效后浏览器无法按照预期工作的说明

Description

对路由中http方法的配置导致cros插件生效后浏览器无法按照预期工作的说明

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)

[cylinder-lee-cn]

update commit

[cylinder-lee-cn]

update title

[kayx23]

Hi, which browser did you use that didn't enable OPTIONS by default?

[github-actions]

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[github-actions]

This pull request/issue has been closed due to lack of activity. If you think that is incorrect, or the pull request requires review, you can revive the PR at any time.