[#305] docs: Add release instructions

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

docs/release-instruction.md

@@ -0,0 +1,41 @@
+# Release instructions
+
+## Pre-release checks
+
+These should run successfully:
+* `go test ./...`;
+* `golangci-lint run ./...`;
+* `go fmt ./...` (should not change any files);
+* `go mog tidy` (should not change any files);
+* `./prepare.sh /path/to/neofs-api/on/your/machine` (should not change any files).
+
+## Writing changelog
+
+Add an entry to the `CHANGELOG.md` following the style established there. Add an
+optional codename(for not patch releases), version and release date in the heading.
+Write a paragraph describing the most significant changes done in this release. Add
+`Fixed`, `Added`, `Removed` and `Updated` sections with fixed bug, new features and
+other changes.
+
+Open Pull Request (must receive at least one approval) and merge this changes.
+
+## Tag a release
+
+Use `vX.Y.Z` tag for releases and `vX.Y.Z-rc.N` for release candidates
+following the [semantic versioning](https://semver.org/) standard.
+
+Update your local `master` branch after approved and merged `CHANGELOG.md` changes.
+Tag a release (must be signed) and push it:
+
+```
+$ git tag -s vX.Y.Z[-rc.N] && git push origin vX.Y.Z[-rc.N]
+```
+
+## Make a Github release
+
+Using Github's web interface create a new release based on just created tag
+with the same changes from changelog and publish it.
+
+## Close github milestone
+
+Close corresponding vX.Y.Z github milestone.