About: Mention the license of the answer icons and example icons.

Because we now bundle them.
About: Change the CC license name for the app icon image.

Because eso.org seems to have changed from
Creative Commons 3.0 Unported
to
Creative Commons Attribution 4.0 International
Remove extra semicolon.
QuestionFragment: Do not use == to compare Strings.

Sometimes I forget that this is not C++.
strings.xml: Escape ' with \.
build.gradle: Update build-tools and compat versions.