Fix typo.

Author: ZeroIntensity

Doc/c-api/init.rst

@@ -2720,7 +2720,7 @@ Operating System Thread APIs
       If the current system uses POSIX threads (also known as "pthreads"),
       this calls :manpage:`pthread_exit(3)`, which attempts to unwind the stack
       and call C++ destructors on some libc implementations. However, if a
-      ``noexcept`` function is reached, they may terminate the process.
+      ``noexcept`` function is reached, it may terminate the process.
       Other systems, such as macOS, do unwinding.
 
       On Windows, this function calls ``_endthreadex``, which kills the thread