docs: Update configuration example

`sha` was renamed to `rev` in pre-commit 1.9.0.

This also changes URLs to use https:// instead of git://, which
works better behind a firewall.

README.md

@@ -1,12 +1,12 @@
 # Rust hooks for pre-commit
 
-[Rust](https://www.rust-lang.org) tools package for [pre-commit](http://pre-commit.com).
+[Rust](https://www.rust-lang.org) tools package for [pre-commit](https://pre-commit.com).
 
 ## Using rust tools with pre-commit
 
 ```yaml
--   repo: git://github.com/doublify/pre-commit-rust
-    sha: master
+-   repo: https://github.com/doublify/pre-commit-rust
+    rev: master
     hooks:
     -   id: fmt
 ```