This change corrects some minor API documentation errors in KCoreAddons noted by Kevin Funk when using clang with the -Wdocumentation flag to note potential Doxygen errors.
See https://paste.kde.org/p6r1o1m5j#line-47. For posterity, the applicable warnings were:
kcoreaddons/src/lib/plugin/kpluginloader.h:442:15: warning: parameter 'errorString' is already documented [-Wdocumentation]
kcoreaddons/src/lib/text/ktexttohtml.h:72:12: warning: parameter 'flags' not found in the function declaration [-Wdocumentation]
kcoreaddons/src/lib/util/kformat.h:185:15: warning: parameter 'specificUnit' not found in the function declaration [-Wdocumentation]