Fix copy & paste error in pidfd_getfd() docs.

Bug: https://github.com/android/ndk/issues/2113
Change-Id: I7c2388165244cfb2becf57f5c53dd822f5e5f067
diff --git a/libc/include/sys/pidfd.h b/libc/include/sys/pidfd.h
index aaf49c9..bd2b01e 100644
--- a/libc/include/sys/pidfd.h
+++ b/libc/include/sys/pidfd.h
@@ -54,7 +54,7 @@
 int pidfd_open(pid_t __pid, unsigned int __flags) __INTRODUCED_IN(31);
 
 /**
- * [pidfd_getfd(2)](https://man7.org/linux/man-pages/man2/pidfd_open.2.html)
+ * [pidfd_getfd(2)](https://man7.org/linux/man-pages/man2/pidfd_getfd.2.html)
  * dups a file descriptor from another process. This file descriptor will have
  * the close-on-exec flag set by default.
  *