This implements coop-cloud/organising#540 by checking if a`release/next` file exists and if so moves it to `release/<tag>`. When no release notes exists it prompts for them.
Reviewed-on: coop-cloud/abra#393
Reviewed-by: moritz <moritz.m@local-it.org>
Co-authored-by: p4u1 <p4u1_f4u1@riseup.net>
Co-committed-by: p4u1 <p4u1_f4u1@riseup.net>
