Utility: Minor documentation error in Debug.h

[Squareys]

As mentioned per gitter :)

[codecov-io]

Codecov Report

Merging #69 into master will decrease coverage by 0.13%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #69      +/-   ##
==========================================
- Coverage   97.61%   97.47%   -0.14%     
==========================================
  Files          80       80              
  Lines        5455     5430      -25     
==========================================
- Hits         5325     5293      -32     
- Misses        130      137       +7

Impacted Files	Coverage Δ
src/Corrade/Utility/Debug.h	100% <ø> (ø)	⬆️
src/Corrade/Utility/Directory.cpp	85.55% <0%> (-2.91%)	⬇️
src/Corrade/Utility/Configuration.cpp	98.12% <0%> (-0.63%)	⬇️
src/Corrade/Utility/AbstractHash.h	96.42% <0%> (-0.13%)	⬇️
src/Corrade/Utility/FileWatcher.cpp	96.55% <0%> (-0.12%)	⬇️
src/Corrade/Interconnect/Emitter.h	98.59% <0%> (-0.06%)	⬇️
src/Corrade/TestSuite/Tester.cpp	93.34% <0%> (-0.02%)	⬇️
src/Corrade/Utility/Arguments.cpp	98.05% <0%> (-0.01%)	⬇️
src/Corrade/TestSuite/Compare/Container.h	100% <0%> (ø)	⬆️
src/Corrade/Interconnect/StateMachine.h	100% <0%> (ø)	⬆️

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[mosra]

Merged, thx!