[ISSUE #11226] docs: fix Chinese best-practice rendering

[NUAAwqy]

Which Issue(s) This PR Fixes

• Fixes [Doc] Remove malformed Markdown from the Chinese best-practice guide #11226

Brief Description

• Removes a malformed empty Markdown link from the Chinese best-practice guide.
• Removes an internal proofreading artifact from the vm.max_map_count bullet.
• Corrects the grammar of the recommendation without changing its meaning.

How Did You Test This Change?

• Ran git diff --check.
• Verified that docs/cn/best_practice.md no longer contains []([]()).
• Reviewed the rendered Markdown structure around the Linux kernel parameter list.