Fix minor typos, use https:// links

Summary: Minor typo fixes and replacement of http://

Test Plan: No major changes, so should work as expected.

Reviewers: KDevelop, pprkut

Reviewed By: KDevelop, pprkut

Subscribers: pprkut, kdevelop-devel

Tags: KDevelop

Differential Revision: https://phabricator.kde.org/D25513