Move General settings to the top

Summary: KDE apps generally (ha ha) have their {nav General} page at the top of the list, so it's the first thing the user sees when they open the {nav Settings} window, but Dolphin is an exception. It puts the {nav General} page //last!// This patch makes Dolphin consistent with other KDE apps by moving the {nav General} page up to the top.

Test Plan: {F5918590}

Reviewers: #dolphin, #kde_applications, elvisangelaccio, ltoscano

Reviewed By: elvisangelaccio, ltoscano

Subscribers: kde-doc-english, ltoscano, elvisangelaccio, kfm-devel

Tags: #dolphin, #documentation

Differential Revision: https://phabricator.kde.org/D13595