docs: Add a brief release checklist.

docs/index.rst

@@ -112,4 +112,5 @@ Contents:
    full-text-search
    translating
    logging
+   release-checklist
    README

docs/release-checklist.md

@@ -0,0 +1,31 @@
+# Zulip server release checklist
+
+This document has reminders of things one might forget to do when
+preparing a new release.
+
+### A week before the release
+
+* Upgrade all Python dependencies in `requirements` to latest
+  upstream versions so they can burn in (use `pip list --outdated`).
+* Update all the strings on Transifex and notify translators that they
+  should translate the new strings to get them in for the next
+  release.
+* Update `changelog.md` with major changes going into the release.
+
+### Final release preparation
+
+* Download updated translation strings from Transifex and commit them.
+* Use `build-release-tarball` to generate a release tarball.
+* Test the new tarball extensively, both new install and upgrade from last
+  release, on both Trusty and Xenial.
+* Do final updates to `changelog.md`.
+* Update `ZULIP_VERSION` in `version.py`.
+* Repeat until release is ready.
+* Draft the release notes; see previous zulip-announce emails for the
+  tooling needed.
+
+### Executing the release
+
+* Post the release tarball on zulip.org and update zulip.org.
+* Create a git tag and push the tag.
+* Email zulip-announce with the release notes.