feat(P27): add Examples section to every module README (D-058)

Each module README (10 primitives + 2 patterns) now has a ## Examples
section before ## Versioning, referencing and excerpting the validated
simple.yaml + complex.yaml (+ mysql.yaml for RDS) example contracts. The
RDS README includes a Multi-engine variation subsection (D-059).

---ci---
project: acdl
phase: 27
milestone: v1.7
status: execute
---/ci---

modules/l1/rds/README.md

@@ -87,6 +87,81 @@ as the regression baseline).
 - **Read replicas** — add `aws_db_instance` with `replicate_source_db` for
   read scaling and DR failover (SOC2 CC9.1, DORA operational resilience).
 
+## Examples
+
+Validated example contracts are in [`examples/`](examples/). The platform-test
+pipeline validates them against `schemas/contract.schema.json`.
+
+### Simple
+
+A minimal deployment:
+
+[`examples/simple.yaml`](examples/simple.yaml)
+```yaml
+# Simple RDS postgres instance
+uses: acdl/pipelines/deploy.yaml@v1.6
+module: rds
+environment: dev
+inputs:
+  engine: postgres
+  engine_version: "16.4"
+  instance_class: db.t3.micro
+  allocated_storage: 20
+  db_name: my_app_db
+  username: db_admin
+  region: us-east-1
+```
+
+### Complex
+
+A production deployment with optional inputs:
+
+[`examples/complex.yaml`](examples/complex.yaml)
+```yaml
+# Complex RDS postgres with multi-AZ + encryption
+uses: acdl/pipelines/deploy.yaml@v1.6
+module: rds
+environment: dev
+inputs:
+  engine: postgres
+  engine_version: "16.4"
+  instance_class: db.r6g.large
+  allocated_storage: 100
+  db_name: my_production_db
+  username: db_admin
+  multi_az: true
+  storage_encrypted: true
+  region: us-east-1
+```
+
+### Multi-engine variation
+
+RDS supports multiple database engines. The `engine` input selects the engine;
+the `engine_version` must match.
+
+#### PostgreSQL
+
+[`examples/simple.yaml`](examples/simple.yaml) — postgres 16.4
+
+#### MySQL
+
+[`examples/mysql.yaml`](examples/mysql.yaml) — mysql 8.4
+
+```yaml
+# RDS mysql variation
+uses: acdl/pipelines/deploy.yaml@v1.6
+module: rds
+environment: dev
+inputs:
+  engine: mysql
+  engine_version: "8.4"
+  instance_class: db.t3.micro
+  allocated_storage: 20
+  db_name: my_mysql_db
+  username: db_admin
+  region: us-east-1
+```
+
 ## Versioning
 
 `1.0.0` — interface MAJOR, behavior MINOR, lifecycle PATCH. MAJOR bumps