Fix function storeImageDataToDisk description

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This merge request fixes / reffers to the following issues: ...

Pull Request Description

####Description
There are some problems in this description

Or using marco like SDWebImageCompat avoid deadlocks

#ifndef dispatch_queue_sync_safe
#define dispatch_queue_sync_safe(queue, block)\
if (strcmp(dispatch_queue_get_label(DISPATCH_CURRENT_QUEUE_LABEL), dispatch_queue_get_label(queue)) == 0) {\
block();\
} else {\
dispatch_sync(queue, block);\
}
#endif

SDWebImage/SDImageCache.h

@@ -154,7 +154,7 @@ typedef void(^SDWebImageCalculateSizeBlock)(NSUInteger fileCount, NSUInteger tot
 /**
  * Synchronously store image NSData into disk cache at the given key.
  *
- * @warning This method is synchronous, make sure to call it from the ioQueue
+ * @warning This method is synchronous, make sure not to call it from the ioQueue
  *
  * @param imageData  The image data to store
  * @param key        The unique image cache key, usually it's image absolute URL