Make tidy happy

Author: Havvy

src/libsyntax/diagnostic_list.rs

@@ -101,19 +101,20 @@ Erroneous code example:
 ```compile_fail,E0541
 #[deprecated(
     since="1.0.0",
-    reason="Example invalid meta item. Should be 'note'") // error: unknown meta item
+    // error: unknown meta item
+    reason="Example invalid meta item. Should be 'note'")
 ]
 fn deprecated_function() {}
 ```
 
-Meta items are the key/value pairs inside of an attribute. The keys provided must be one of the
-valid keys for the specified attribute.
+Meta items are the key/value pairs inside of an attribute. The keys provided
+must be one of the valid keys for the specified attribute.
 
-To fix the problem, either remove the unknown meta item, or rename it if you provided the wrong
-name.
+To fix the problem, either remove the unknown meta item, or rename it if you
+provided the wrong name.
 
-In the erroneous code example above, the wrong name was provided, so changing it to the right name
-fixes the error.
+In the erroneous code example above, the wrong name was provided, so changing it
+to the right name fixes the error.
 
 ```
 #[deprecated(