Fix unstable check.

Author: ehuss

src/types/never.md

@@ -7,8 +7,8 @@ The never type `!` is a type with no values, representing the result of
 computations that never complete. Expressions of type `!` can be coerced into
 any other type.
 
-```rust,should_panic
-#![feature(never_type)]
+<!-- ignore: unstable -->
+```rust,ignore
 let x: ! = panic!();
 // Can be coerced into any type.
 let y: u32 = x;

stable-check/Cargo.lock

@@ -26,18 +26,15 @@ fn check_directory(dir: &Path) -> Result<(), Box<dyn Error>> {
         let path = entry.path();
 
         if path.is_dir() {
-            continue;
+            return check_directory(&path);
         }
 
         let mut file = File::open(&path)?;
         let mut contents = String::new();
         file.read_to_string(&mut contents)?;
 
         if contents.contains("#![feature") {
-            // `attributes.md` contains this and it is legitimate.
-            if !contents.contains("#![feature(feature1, feature2, feature3)]") {
-                return Err(From::from(format!("Feature flag found in {:?}", path)));
-            }
+            return Err(From::from(format!("Feature flag found in {:?}", path)));
         }
     }