docs(module:*): debug demos

[wzhudev]

Add debug: true in the yaml meta, we could me a demo only visible in local development. It would be convenient to debug reproductions from the community.

允许在 demo 中增加 debug: true 属性，来让这个 demo 只出现在本地开发环境中，这样调试用户提供的复现时就会方便一些。

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/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)
[x] 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

[zorro-bot]

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[codecov]

Codecov Report

Merging #7408 (5dd109f) into master (f09ba57) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #7408      +/-   ##
==========================================
- Coverage   91.61%   91.57%   -0.05%     
==========================================
  Files         487      496       +9     
  Lines       16043    16316     +273     
  Branches     2610     2531      -79     
==========================================
+ Hits        14698    14941     +243     
- Misses       1031     1050      +19     
- Partials      314      325      +11     

Impacted Files	Coverage Δ
components/core/config/config.ts	100.00% <0.00%> (ø)
components/mention/mention.module.ts	100.00% <0.00%> (ø)
components/transfer/transfer.component.ts	93.27% <0.00%> (ø)
components/segmented/types.ts	100.00% <0.00%> (ø)
components/core/config/css-variables.ts	87.23% <0.00%> (ø)
components/core/color/generate.ts	77.27% <0.00%> (ø)
components/segmented/segmented.component.ts	95.00% <0.00%> (ø)
components/core/util/can-use-dom.ts	100.00% <0.00%> (ø)
components/core/animation/thumb.ts	100.00% <0.00%> (ø)
components/segmented/segmented.module.ts	100.00% <0.00%> (ø)
... and 8 more

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