Summary:
Problems with the current strings:
- Incorrect capitalization
- Grammatical errors ("to show the latter")
- Inappropriate obscure references ("This might remind you of something.")
- Redundancy (mentioning "showing the desktop" when the KCM's header already shows this)

The above issues are fixed.

Test Plan:
Before: {F8129332}
After: {F8129331}

Reviewers: #vdg, #kwin, filipf, zzag

Reviewed By: #vdg, #kwin, filipf, zzag

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D27630