licensing terms of plasma dictionary runner

[Harald Sitter]

Hey Jason!

Hope you are doing well.
I've just noticed that the dictionary runner you've made for Plasma
doesn't really have licensing terms in its source files.

https://cgit.kde.org/kdeplasma-addons.git/tree/runners/dictionary/dictionaryrunner.cpp

It'd be really grand if you could specify which terms apply so we can
fix up the headers accordingly.

https://community.kde.org/Policies/Licensing_Policy

Thanks!
HS