chore: correctly use local language in document site

[cipchk]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ng-alain/delon/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[ ] No

Other information

[ng-alain-bot]

Preview is ready!

[codecov]

Codecov Report

Merging #1648 (b36c7f3) into master (5dc859e) will not change coverage.
The diff coverage is n/a.

❗ Current head b36c7f3 differs from pull request most recent head 65cf3f9. Consider uploading reports for the commit 65cf3f9 to get more accurate results

@@           Coverage Diff           @@
##           master    #1648   +/-   ##
=======================================
  Coverage   95.57%   95.57%           
=======================================
  Files         281      281           
  Lines        8741     8741           
  Branches     1732     1732           
=======================================
  Hits         8354     8354           
  Misses        319      319           
  Partials       68       68           

Files Changed	Coverage Δ
packages/theme/src/services/i18n/i18n-url.guard.ts	100.00% <ø> (ø)