doc: fix minor typo

library/std/src/thread/mod.rs

@@ -116,7 +116,7 @@
 //! Threads are able to have associated names for identification purposes. By default, spawned
 //! threads are unnamed. To specify a name for a thread, build the thread with [`Builder`] and pass
 //! the desired thread name to [`Builder::name`]. To retrieve the thread name from within the
-//! thread, use [`Thread::name`]. A couple examples of where the name of a thread gets used:
+//! thread, use [`Thread::name`]. A couple of examples where the name of a thread gets used:
 //!
 //! * If a panic occurs in a named thread, the thread name will be printed in the panic message.
 //! * The thread name is provided to the OS where applicable (e.g., `pthread_setname_np` in