Outdent example, preserving nested fence

src/doc/rustdoc/src/what-is-rustdoc.md

@@ -98,7 +98,7 @@ documentation for them as well!
 `rustdoc` can also generate HTML from standalone Markdown files. Let's
 give it a try: create a `README.md` file with these contents:
 
-```text
+````text
 # Docs
 
 This is a project to test out `rustdoc`.
@@ -112,7 +112,7 @@ give it a try: create a `README.md` file with these contents:
     1 + 1
 }
 ```
-```
+````
 
 And call `rustdoc` on it: