docs: Add releasing guide and new language note

Also removes permalink check

.pre-commit-config.yaml

@@ -22,7 +22,6 @@ repos:
       - id: end-of-file-fixer
         exclude: fixtures
       - id: mixed-line-ending
-      - id: check-vcs-permalinks
       - id: check-merge-conflict
       - id: check-added-large-files
       # - id: no-commit-to-branch

README.md

@@ -36,3 +36,6 @@ instance. Join in and help translate for your language!
 </a>
 
 [![Translation status](https://translations.metabrainz.org/widget/email/email-templates/multi-auto.svg)](https://translations.metabrainz.org/engage/email/)
+
+When adding a new language, please make sure to add the language
+to the [list of supported languages](https://github.com/metabrainz/mb-mail-service/blob/main/Cargo.toml#L10).

docs/RELEASING.md

@@ -0,0 +1,7 @@
+# Releasing
+
+1. Update the version in `Cargo.toml` (and update `Cargo.lock`, `cargo` will do
+   this for you).
+2. Tag and push the commit with the new version number. For example, `v0.3.4`
+3. Wait for the CI to complete. This will build Docker images and publish
+   them to Docker Hub with the correct tags.