docs: Add release checklist

Author: foxcpp

.github/releases.md

@@ -0,0 +1,34 @@
+# Release preparation
+
+1. Run linters, fix all simple warnings. If the behavior is intentional - add
+`nolint` comment and explanation. If the warning is non-trviail to fix - open
+an issue.
+```
+golangci-lint run
+```
+
+2. Run unit tests suite. Verify that all disabled tests are not related to
+   serious problems and have corresponding issue open.
+```
+go test ./...
+```
+
+3. Run integration tests suite. Verify that all disabled tests are not related
+   to serious problems and have corresponding issue open.
+```
+cd tests/
+./run.sh
+```
+
+4. Use environment configuration from maddy-repro bundle
+   (https://foxcpp.dev/maddy-repro) to build release artifacts.
+
+5. Create detached PGP signatures for artifacts using key
+   3197BBD95137E682A59717B434BB2007081396F4.
+
+6. Create sha256sums file for artifacts.
+
+7. Create PGP-signed Git tag and write release notes into its description.
+
+8. Push Git tag to GitHub. Create release on GitHub using the same text for
+   release notes. Attach signed artifacts and sha256sums file.