fix(docs): backspace in header

[Jocs]

close https://github.com/dream-num/univer-pro/issues/1504

Pull Request Checklist

• Related tickets or issues have been linked in the PR description (or missing issue).
• Naming convention is followed (do please check it especially when you created new plugins, commands and resources).
• Unit tests have been added for the changes (if applicable).
• Breaking changes have been documented (or no breaking changes introduced in this PR).

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 26.50%. Comparing base (f93a229) to head (3c23d56).

Files	Patch %	Lines
...kages/docs/src/commands/commands/delete.command.ts	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #2703      +/-   ##
==========================================
+ Coverage   26.49%   26.50%   +0.01%     
==========================================
  Files        1668     1668              
  Lines       89476    89476              
  Branches    18852    18852              
==========================================
+ Hits        23709    23719      +10     
+ Misses      65767    65757      -10     

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