Rollup merge of #81697 - xfix:every-doc-alias, r=Mark-Simulacrum
Rollup merge of #81697 - xfix:every-doc-alias, r=Mark-Simulacrum

Add "every" as a doc alias for "all".

This matches [Array#every](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/every) in JavaScript.

Oddly enough, `core::iter::Iterator::all` appears twice. This appears to be a rustdoc bug which I decided to fill in as #81696.

![image](https://user-images.githubusercontent.com/1297598/106717890-94f43e80-6600-11eb-9428-2cd425823df9.png)

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