Auto merge of #87820 - elichai:patch-2, r=kennytm
Auto merge of #87820 - elichai:patch-2, r=kennytm

Replace read_to_string with read_line in Stdin example

The current example results in infinitely reading from stdin, which can confuse newcomers trying to read from stdin.
(`@razmag` encountered this while learning the language from the docs)

aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust