correct docs ding

Signed-off-by: Brian L. Troutwine <[email protected]>

Author: blt

src/sys/timer.rs

@@ -1,9 +1,9 @@
 //! Timer API via signals.
 //!
 //! Timer is a POSIX API to create timers and get expiration notifications
-//! through queued signals for the current process. This is similar to
-//! [`crate::sys::timerfd`] but available on systems other than Linux and makes
-//! use of Unix signals instead of file polling.
+//! through queued Unix signals, for the current process. This is similar to
+//! Linux's timerfd mechanism, except that API is specific to Linux and makes
+//! use of file polling.
 //!
 //! For more documentation, please read [timer_create](https://pubs.opengroup.org/onlinepubs/9699919799/functions/timer_create.html).
 //!