feat(module:descriptions): add nzColon to toggle colon

[wzhudev]

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
[x] 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
[x] No

Other information

It works with the latest style update #3921.

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[codecov]

Codecov Report

Merging #3923 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3923      +/-   ##
==========================================
+ Coverage   95.24%   95.24%   +<.01%     
==========================================
  Files         726      726              
  Lines       14672    14673       +1     
  Branches     1910     1910              
==========================================
+ Hits        13974    13975       +1     
  Misses        260      260              
  Partials      438      438

Impacted Files	Coverage Δ
...mponents/descriptions/nz-descriptions.component.ts	98.73% <100%> (+0.01%)	⬆️

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[vthinkxie]

LGTM