fix(docs): Improve certificate manager documentation with detailed examples and custom implementation guide

readme.md

@@ -113,6 +113,54 @@ const certManager = new MongoCertManager({
 });
 ```
 
+SmartAcme uses the `ICertManager` interface for certificate storage. Two built-in implementations are available:
+
+- **MemoryCertManager**
+  - In-memory storage, suitable for testing or ephemeral use.
+  - Import example:
+    ```typescript
+    import { MemoryCertManager } from '@push.rocks/smartacme';
+    const certManager = new MemoryCertManager();
+    ```
+
+- **MongoCertManager**
+  - Persistent storage in MongoDB (collection: `SmartacmeCert`).
+  - Import example:
+    ```typescript
+    import { MongoCertManager } from '@push.rocks/smartacme';
+    const certManager = new MongoCertManager({
+      mongoDbUrl: 'mongodb://yourmongoURL',
+      mongoDbName: 'yourDbName',
+      mongoDbPass: 'yourDbPassword',
+    });
+    ```
+
+#### Custom Certificate Managers
+
+To implement a custom certificate manager, implement the `ICertManager` interface and pass it to `SmartAcme`:
+
+```typescript
+import type { ICertManager, Cert as SmartacmeCert } from '@push.rocks/smartacme';
+import { SmartAcme } from '@push.rocks/smartacme';
+
+class MyCustomCertManager implements ICertManager {
+  async init(): Promise<void> { /* setup storage */ }
+  async get(domainName: string): Promise<SmartacmeCert | null> { /* lookup cert */ }
+  async put(cert: SmartacmeCert): Promise<SmartacmeCert> { /* store cert */ }
+  async delete(domainName: string): Promise<void> { /* remove cert */ }
+  async close?(): Promise<void> { /* optional cleanup */ }
+}
+
+// Use your custom manager:
+const customManager = new MyCustomCertManager();
+const smartAcme = new SmartAcme({
+  accountEmail: 'youremail@example.com',
+  certManager: customManager,
+  environment: 'integration',
+  challengeHandlers: [], // add your handlers
+});
+```
+
 ### Environmental Considerations
 
 When creating an instance of `SmartAcme`, you can specify an `environment` option. This is particularly useful for testing, as you can use the `integration` environment to avoid hitting rate limits and for testing your setup without issuing real certificates. Switch to `production` when you are ready to obtain actual certificates.