fix(docs): incorrect snippets

[ematipico]

Summary

@togami2864 noEmptyBlock snippet fails, please fix it whenever you can
@minht11 a snippet is failing, it's not returning any diagnostics. Please fix it
@chansuke next time, please make sure that the code blocks are correct. Also, one of the code snippets didn't emit diagnostics. Please fix it
@fujiyamaorange please, next time make sure to put valid code inside the snippets

Test Plan

Merge it. It will fix the website

[minht11]

@ematipico how can see what diagnostic was or was not generated?

[ematipico]

The code that checks that is in the website repository for now. We plan to bring it back here. You should run cargo run -p codegen rules.

Anyway, the cases that are failing aren't inside the tests, so we should at least make sure that we use invalid cases that are covered by our tests.

We have import "./foo/"; but not import "./foo";

[codspeed-hq]

CodSpeed Performance Report

Merging #3059 will improve performances by 6.97%

_{Comparing fix/incorrect-docs (c34d3de) with main (378c05e)}

Summary

⚡ 1 improvements
✅ 91 untouched benchmarks

Benchmarks breakdown

	Benchmark	main	fix/incorrect-docs	Change
⚡	pure.css[cached]	4 ms	3.7 ms	+6.97%