Minor improves for Krita User Manual
Summary:
Change http:// to https://
Capitalize and end punctuation
Test Plan: I report a question more and apply all changes
Reviewers: Krita: Manual, woltherav
Reviewed By: Krita: Manual, woltherav
Subscribers: woltherav
Tags: Krita: Manual
Differential Revision: https://phabricator.kde.org/D20409