This removes the link to the KDevelop setup video tutorial as it's
now outdated.
IDE screenshots were also optimized losslessly using
`oxipng -o6 --strip --zopfli`.
See #3485.
Also added some screenshots fort the "Importing the project" section
Since I was doing these changes I updated also the following:
- added images for the build and run steps for Qt Creator (also changed
one line to match the screenshot taken on Linux in this case)
- fixed typo It's called "Qt Creator" not "QtCreator" althought packages
and launchers sometimes call it like that (I tend to make that mistake
too).