message: Add missing backtick, fix cargo update script
  This PR adds a missing backtick when referring to `wrangler` in the
  README, and fixes the cargo update script to not install directly from
  GitHub (from master)
diff: @@ -188,12 +188,12 @@ Wrangler can be installed both through [npm](https://www.npmjs.com/get-npm) and
  $ brew install openssl@1.1
  ```
  -1. Updating `wrangler:
  +1. Updating `wrangler`:
  To get the latest version of Wrangler, using Cargo, run:
  ```sh
  - cargo install --git https://github.com/cloudflare/wrangler --force
  + cargo install wrangler --force
  ```
  To get the latest version of Wrangler, using NPM, run:
  