Fix grammar error

Author: tiif

src/shims/unix/linux/epoll.rs

@@ -448,8 +448,8 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         Ok(Scalar::from_i32(num_of_events))
     }
 
-    /// This function takes in ready list and returns EpollEventInstance with file descriptions
-    /// that are not closed.
+    /// This function takes in ready list and returns EpollEventInstance with file description
+    /// that is not closed.
     fn ready_list_next(
         &self,
         ready_list: &mut BTreeMap<(FdId, i32), EpollEventInstance>,