[chinese/bash] A wrong code

At the begining of if part, the `-ne` should be `!=` for string compare.

Start with the Chinese Bash tutorial referenced by the issue tag (`chinese/bash`) and open the corresponding markdown lesson file. Find the initial `if` example using `-ne`, and confirm it should be changed to `!=` for string comparison. Since this is docs-only, there are no explicit tests to run; the issue is done when the snippet in that page uses the corrected operator and formatting remains intact.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.