Fix a typo in 'Direct plugin communication' documentation code example

[younesmln]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers:

[lukastaegert]

Awesome, thanks for spotting!

[codecov]

Codecov Report

Merging #4406 (5bb4a26) into master (69eb721) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4406   +/-   ##
=======================================
  Coverage   98.72%   98.72%           
=======================================
  Files         204      204           
  Lines        7319     7319           
  Branches     2081     2081           
=======================================
  Hits         7226     7226           
  Misses         34       34           
  Partials       59       59           

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