Added compiler flags to example code, removed unexpected curly

Author: jwhite927

src/librustc_error_codes/error_codes/E0637.md

@@ -2,7 +2,7 @@ An underscore `_` character has been used as the identifier for a lifetime,
 or a const generic has been borrowed without an explicit lifetime.
 
 Erroneous example with an underscore:
-```
+```compile_fail,E0106,E0637
 fn foo<'_>(str1: &'_ str, str2: &'_ str) -> &'_ str {}
     // ^^ `'_` is a reserved lifetime name
 ```
@@ -19,7 +19,7 @@ fn <'a>(str1: &'a str, str2: &'a str) -> &'a str {}
 ```
 
 Erroneous example with const generic:
-```
+```compile_fail,E0637
 struct A<const N: &u8>;
 //~^ ERROR `&` without an explicit lifetime name cannot be used here
 trait B {}
@@ -35,7 +35,6 @@ impl<const N: &u8> B for A<N> {}
 
 fn bar<const N: &u8>() {}
 //~^ ERROR `&` without an explicit lifetime name cannot be used here
-}
 ```
 
 Const generics cannot be borrowed without specifying a lifetime.The
@@ -56,6 +55,5 @@ impl<const N: &'a u8> A<N> {
 impl<const N: &'a u8> B for A<N> {}
 
 fn bar<const N: &'a u8>() {}
-}
 ```
 [bk-no]: https://doc.rust-lang.org/book/appendix-02-operators.html#non-operator-symbols