docs(pusher): re-add dropped server library, interoperability, and count details

[SimonWoolf]

Re-adds some information to the Pusher Adapter page that used to be available on the old support article (3000055086 — Using the Ably Pusher protocol adaptor) but was removed in the transition to the current docs page.

What's re-added

• Server-side (REST) Pusher library configuration — the page advertised the REST features as supported but never showed how to configure a serverside library. Adds a Ruby example with the host, app_id/key/secret split, and TLS option, plus an options table.
• Interoperability note — Pusher and Ably client libraries can be used side by side against the same channels (e.g. publish/subscribe with Pusher, fetch history via the Ably REST API).
• User and subscriber count behaviour — both only work on presence channels, with the distinction that user count is uniqued by clientId while subscriber count is the raw presence-set size.

🤖 Generated with Claude Code

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on this repository. Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: b45f558e-ed54-4d9a-9572-6d7c285d844d

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch pusher-adapter-readd-dropped-info

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[m-hulbert]

Just a few small suggested tidy ups.

[SimonWoolf]

Applied all suggested changes