feat(build): use prettyplease to format output (#890) (#904)

examples/helloworld-tutorial.md

@@ -26,7 +26,6 @@ feature.
 
 ```bash
 $ rustup update
-$ rustup component add rustfmt
 ```
 
 ## Defining the HelloWorld service

examples/routeguide-tutorial.md

@@ -47,12 +47,6 @@ Change your current directory to Tonic's repository root:
 $ cd tonic
 ```
 
-Tonic uses `rustfmt` to tidy up the code it generates, so we'll make sure it's installed.
-
-```shell
-$ rustup component add rustfmt
-```
-
 Run the server
 ```shell
 $ cargo run --bin routeguide-server