docs(caching): update get cache method description

Author: Sufiane

content/techniques/caching.md

@@ -38,10 +38,10 @@ constructor(@Inject(CACHE_MANAGER) private cacheManager: Cache) {}
 
 > info **Hint** The `Cache` class is imported from the `cache-manager`, while `CACHE_MANAGER` token from the `@nestjs/common` package.
 
-The `get` method on the `Cache` instance (from the `cache-manager` package) is used to retrieve items from the cache. If the item does not exist in the cache, an exception will be thrown.
+The `get` method on the `Cache` instance (from the `cache-manager` package) is used to retrieve items from the cache. If the item does not exist in the cache, undefined will be returned.
 
 ```typescript
-const value = this.cacheManager.get('key');
+const value = await this.cacheManager.get('key');
 ```
 
 To add an item to the cache, use the `set` method: