docs: add LogConsumer class and enabled method documentation

Author: mertcanaltin

doc/api/logger.md

@@ -8,3 +8,33 @@
 
 The `node:logger` module provides structured logging capabilities for Node.js
 applications.
+
+## Class: `LogConsumer`
+
+### `consumer.enabled(level)`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* `level` {string} The log level to check (e.g., `'debug'`, `'info'`, `'warn'`,
+  `'error'`, `'fatal'`).
+* Returns: {boolean} `true` if the level is enabled, `false` otherwise.
+
+Checks if a specific log level is enabled for this consumer.
+
+This method returns `false` for unknown log levels without throwing an error.
+Log levels are case-sensitive and must be one of the predefined levels:
+`'trace'`, `'debug'`, `'info'`, `'warn'`, `'error'`, `'fatal'`.
+
+```js
+const { LogConsumer } = require('node:logger');
+
+const consumer = new LogConsumer({ level: 'info' });
+
+console.log(consumer.enabled('debug')); // false (below threshold)
+console.log(consumer.enabled('info'));  // true
+console.log(consumer.enabled('error')); // true
+console.log(consumer.enabled('DEBUG')); // false (unknown level - case sensitive)
+console.log(consumer.enabled('unknown')); // false (unknown level)
+```