readv.2: tfix

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
diff --git a/man2/readv.2 b/man2/readv.2
index d81e0ff..8190c9b 100644
--- a/man2/readv.2
+++ b/man2/readv.2
@@ -291,7 +291,7 @@
 .BR preadv2 ()
 and
 .BR pwritev2 ()
-first appeared in Linux 4.6
+first appeared in Linux 4.6.
 .SH CONFORMING TO
 .BR readv (),
 .BR writev ():