Correct Shelter's license

It looks like Shelter's license has been changed to GPL v3.0. So, adjusting the comparison to take that into account.

Also, I noticed another issue in the FAQ document. The "file an issue" link in the following paragraph appears to be broken:

If TestDPC works flawlessly but Insular does not, please file an issue with logcat attached for us to further analyze. If you are not familiar with logcat, please “Take bug report” in system “Settings - (System) - Developer options” and share the bug-report privately.

I thought of fixing it but I don't see the corresponding source in faq.md which is confusing 🤔