v0.15 release notes (pomerium#2409)

RELEASING.md

@@ -0,0 +1,40 @@
+# Overall process
+
+1. Add new branch to netlify build settings (new release branch only)
+2. Request new subdomain for netlify TLS certificate (new release branch only)
+3. Generate changelog
+4. Update docs/upgrading.md for major/minor releases
+5. Update vuepress branch config in `config.js`
+   1. Set new default text nav
+   2. Add new branch to item list
+6. Create a new release branch for major/minor releases, eg `0-15-0`, off master.  Patch releases use existing release branches.
+7. Create Github release with name and tag matching `v[version]` on the appropriate release branch.
+8. Copy/paste changelog from generated output into Github release notes
+9.  GH automation should take it from there and build/upload artifacts
+10. Update default branch on netlify to new release branch (new release branch only)
+
+# Changelog generation
+
+`./scripts/changelog.sh [previous version] [next version] [branch]`
+
+This script requires docker running and GITHUB_TOKEN set with a PAT.
+
+The changelog will be written to changelog.out
+
+## Major/minor release example
+
+```bash
+GITHUB_TOKEN=XXXXXX ./changelog.sh v0.14.0 v0.15.0 master changelog.out
+```
+
+## Patch release example
+
+```bash
+GITHUB_TOKEN=XXXXXX ./changelog.sh v0.14.6 v0.14.7 master changelog.out
+```
+
+# Release branches
+
+For each major or minor release, we create a release branch `[major]-[minor]-0`.  This is to allow feature freeze ahead of actual release and provide a stable branch to apply patches onto for bug fixes.
+
+These branches are to be protected and may receive updates via backport or direct PR.