update 8.0 branch by changes in 7.x (master)
update 8.0 branch by changes in 7.x (master)

- merging `master` into `8.0` manually because it wasn't mergeable automatically anymore
- the conflict appeared because FAQ was appended both in #875 and #912 (in docs/introduction/faq-and-common-issues.md only)
- the conflict was resolved by appending the changes from `8.0` after the changes from `master`

shopsys/coding-standards