docs: keep each service README inside its own directory

A service README now describes only its own service: no links to other
services or to the root, and no restating of the shared conventions that
the root README and CLAUDE.md already carry. Each service is a separate
Coolify app on a <service>/** watch path, so a cross-link made editing one
service redeploy another. The rule is recorded at the root; the alloy
compose comment now points at a heading that exists.

couchbase/README.md

@@ -1,13 +1,12 @@
 # couchbase
 
-[Couchbase Server](https://www.couchbase.com), single node.
-
-Uses `docker-compose.yml`, publishes ports, and sets `container_name: db` —
-unlike the platform-managed services described in the
-[root README](../README.md).
+[Couchbase Server](https://www.couchbase.com), single node, defined in
+`docker-compose.yml` with `container_name: db`.
 
 ## Networking
 
+Publishes its ports on the host:
+
 | Ports | Purpose |
 | --- | --- |
 | `8091-8097` | Cluster manager, views, query, search, analytics, eventing |