ci: remove the broken changeset Release workflow (we publish manually)

release.yml failed on every push to main — it ran 'yarn install --frozen-lockfile'
against a stale yarn.lock and assumed a changeset-based flow we don't use (we
bump + 'npm publish' by hand). Drop the workflow + its unused Discord notify, and
point CONTRIBUTING at the manual npm flow.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: agviegas

.github/workflows/release.yml

@@ -17,30 +17,14 @@ npm run build:cli      # CLI only
 
 ### Publishing a new version
 
-Publishing is handled automatically by CI when a PR with changesets is merged to `main`.
-
-**1. Create a changeset (developer does this with their changes):**
-
-```bash
-yarn changeset
-# Pick the bump type (patch / minor / major) and write a summary
-# This creates a .changeset/<random-name>.md file — commit it with your PR
-```
-
-**2. Merge the PR to `main`:**
-
-CI will automatically:
-- Consume the changeset files
-- Bump `package.json` version and update `CHANGELOG.md`
-- Commit the version bump back to `main`
-- Build and publish to npm
-
-**Manual publishing (if CI is not available):**
+Publishing is **manual** via `npm`. From `main` with a clean working tree:
 
 ```bash
-yarn version           # Consume changesets, bump version
-yarn build
-yarn changeset publish
+npm version patch --no-git-tag-version   # bump package.json (default to a patch)
+npm publish                              # prepublishOnly runs the full build first
+git commit -am "chore(release): @thatopen/services <version>"
+git push
 ```
 
-Keep in mind the importance of semver — don't release a major for non-breaking changes.
+Keep semver in mind, but default to a **patch** unless a maintainer explicitly
+calls for a minor or major.