Auto merge of #232 - rust-lang:update-docs, r=fmoko

chore: Update docs for 2.0

Only merge this once we're ready to release 2.0.

CONTRIBUTING.md

@@ -35,8 +35,11 @@ You want to make sure where in the file you add your exercise. If you're not sur
 ```diff
   ...
 + [[exercises]]
++ name = "yourTopicN"
 + path = "exercises/yourTopic/yourTopicN.rs"
 + mode = "compile"
++ hint = """
++ Some kind of useful hint for your exercise."""
   ...
 ```
 

README.md

@@ -80,10 +80,15 @@ This will do the same as watch, but it'll quit after running.
 In case you want to go by your own order, or want to only verify a single exercise, you can run:
 
 ```bash
-rustlings run exercises/path/to/exercise.rs
+rustlings run myExercise1
 ```
 
-In case you get stuck, there is usually a hint at the bottom of each exercise.
+In case you get stuck, you can run the following command to get a hint for your
+exercise:
+
+``` bash
+rustlings hint myExercise1
+```
 
 ## Testing yourself