Rollup merge of #38662 - agl:patch-2, r=frewsxcv
Rollup merge of #38662 - agl:patch-2, r=frewsxcv

Use "an" before "i32"

(Minor typo fix.)

Since the word `i32` starts with a vowel, the indefinite article should use "an", not "a" \[[1](http://www.dictionary.com/browse/an)\]. (Previously there was one instance of "an i32" and two instances of "a i32", so at least something is wrong!) Since I believe that "an" is the correct form, I aligned everything with that.

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