GitLab Next

Images should be stored in the corresponding location to the release
post item.

- data/release_posts/unreleased -> images/unreleased
- data/release_posts/13_6 -> images/13_6

Previously, validation assumed it would only be run on files in the
unreleased directory. This has now been generalized so the validation
script can also be re-run after assembly.

This is useful for verifying content validity in the final stages of the
release post process.