Fixes typo in SDImageCacheConfig maxDiskAge info
Fixes typo in SDImageCacheConfig maxDiskAge info

dreampiggy/SDWebImage,rs/SDWebImage,dreampiggy/SDWebImage,awkward/SDWebImage,awkward/SDWebImage,zhang-yawei/SDWebImage,tualatrix/SDWebImage,dreampiggy/SDWebImage,awkward/SDWebImage