Fix some small mistakes

Author: poliorcetics

src/librustc_error_codes/error_codes/E0432.md

@@ -6,12 +6,6 @@ Erroneous code example:
 use something::Foo; // error: unresolved import `something::Foo`.
 ```
 
-Paths in `use` statements are relative to the crate root. To import items
-relative to the current and parent modules, use the `self::` and `super::`
-prefixes, respectively. Also verify that you didn't misspell the import
-name and that the import exists in the module from where you tried to
-import it. Example:
-
 In Rust 2015, paths in `use` statements are relative to the crate root. To
 import items relative to the current and parent modules, use the `self::` and
 `super::` prefixes, respectively.
@@ -41,13 +35,13 @@ the crate root):
 extern crate core; // Required to use the `core` crate in Rust 2015.
 
 use core::any;
-# fn main() { assert!(false); }
+# fn main() {}
 ```
 
 In Rust 2018 the `extern crate` declaration is not required and you can instead
 just `use` it:
 
-```
+```edition2018
 use core::any; // No extern crate required in Rust 2018.
 # fn main() {}
 ```