[Qt][C++] Updated cpp-qt5-client doc

[basyskom-dege]

Added missing security feature support in the documentation

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Added missing security feature support for the cpp-qt5-generator.

PING @wing328 @etherealjoy

[basyskom-dege]

Will this change be overwritten in the future since i just changed it over the Website?

[wing328]

@basyskom-dege thanks for the PR. You will need to update https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppQt5ClientCodegen.java#L41-L45 instead. Let us know if you need any help.

[basyskom-dege]

changed on Java-level. Should be fine now.

[wing328]

FYI @ravinikam (2017/07) @stkrwork (2017/07) @etherealjoy (2018/02) @MartinDelille (2018/03) @muttleyxd (2019/08)