Bump iOS min in Readme (#20805)
Bump iOS min in Readme (#20805)

Summary:
iOS 8 was dropped as of 0.56.
Pull Request resolved: https://github.com/facebook/react-native/pull/20805

Differential Revision: D9481968

Pulled By: hramos

fbshipit-source-id: 23e74ac3145ba92e2c119be365f2435e290c3f61

facebook/react-native,pandiaraj44/react-native,myntra/react-native,myntra/react-native,exponentjs/react-native,exponentjs/react-native,hammerandchisel/react-native,myntra/react-native,hoangpham95/react-native,janicduplessis/react-native,facebook/react-native,facebook/react-native,javache/react-native,myntra/react-native,exponent/react-native,javache/react-native,javache/react-native,janicduplessis/react-native,javache/react-native,exponentjs/react-native,hammerandchisel/react-native,exponent/react-native,pandiaraj44/react-native,arthuralee/react-native,exponentjs/react-native,javache/react-native,arthuralee/react-native,myntra/react-native,myntra/react-native,facebook/react-native,janicduplessis/react-native,hammerandchisel/react-native,javache/react-native,myntra/react-native,facebook/react-native,janicduplessis/react-native,arthuralee/react-native,hammerandchisel/react-native,exponent/react-native,exponentjs/react-native,hammerandchisel/react-native,exponentjs/react-native,hammerandchisel/react-native,pandiaraj44/react-native,myntra/react-native,arthuralee/react-native,pandiaraj44/react-native,pandiaraj44/react-native,hoangpham95/react-native,pandiaraj44/react-native,janicduplessis/react-native,facebook/react-native,hoangpham95/react-native,hoangpham95/react-native,hoangpham95/react-native,facebook/react-native,pandiaraj44/react-native,javache/react-native,hoangpham95/react-native,exponent/react-native,hoangpham95/react-native,janicduplessis/react-native,exponent/react-native,hoangpham95/react-native,hammerandchisel/react-native,exponent/react-native,exponent/react-native,facebook/react-native,exponent/react-native,javache/react-native,javache/react-native,janicduplessis/react-native,exponentjs/react-native,janicduplessis/react-native,arthuralee/react-native,facebook/react-native,exponentjs/react-native,myntra/react-native,hammerandchisel/react-native,pandiaraj44/react-native