Add back credits for the former ODT backend

Even though we don't ship it anymore, it was still a valuable contribution
from its author.

aboutdata.h

@@ -29,7 +29,7 @@ inline KAboutData okularAboutData()
                      QStringLiteral("https://okular.kde.org"));
 
     about.addAuthor(QStringLiteral("Pino Toscano"), i18n("Former maintainer"), QStringLiteral("pino@kde.org"));
-    about.addAuthor(QStringLiteral("Tobias Koenig"), i18n("Lots of framework work, FictionBook backend"), QStringLiteral("tokoe@kde.org"));
+    about.addAuthor(QStringLiteral("Tobias Koenig"), i18n("Lots of framework work, FictionBook backend and former ODT backend"), QStringLiteral("tokoe@kde.org"));
     about.addAuthor(QStringLiteral("Albert Astals Cid"), i18n("Developer"), QStringLiteral("aacid@kde.org"));
     about.addAuthor(QStringLiteral("Piotr Szymanski"), i18n("Created Okular from KPDF codebase"), QStringLiteral("djurban@pld-dc.org"));
     about.addAuthor(QStringLiteral("Enrico Ros"), i18n("KPDF developer"), QStringLiteral("eros.kde@email.it"));