memoryConfig not optional for Storage.init as comment says.

``` /// Initialize storage with configuration options.
///
/// - Parameters:
/// - diskConfig: Configuration for disk storage
/// - memoryConfig: *Optional*. Pass config if you want memory cache
/// - Throws: Throw StorageError if any.
public convenience init(diskConfig: DiskConfig, memoryConfig: MemoryConfig, transformer: Transformer) throws {
let disk = try DiskStorage(config: diskConfig, transformer: transformer)
let memory = MemoryStorage(config: memoryConfig)
let hybridStorage = HybridStorage(memoryStorage: memory, diskStorage: disk)
self.init(hybridStorage: hybridStorage)
}
```

This says `memoryConfig` should be Optional, but it's not. Not sure which is the typo.

Review the public Storage.init(diskConfig:memoryConfig:transformer:) declaration shown in the issue and inspect its callers to determine whether memoryConfig is intended to be optional. Make the signature and documentation consistent, then verify the initializer behavior and existing call sites.

Scritto dal modello di indicizzazione a partire dal testo della issue.