missing dots after ".%P pp"; the case of btree(3) was

reported by Fabio Scotoni <fabio at esse dot ch>;
also garbage collect one .Tn while here

src/lib/libutil/ohash_init.3

@@ -1,4 +1,4 @@
-.\"	$OpenBSD: ohash_init.3,v 1.2 2014/05/13 14:01:41 jmc Exp $
+.\"	$OpenBSD: ohash_init.3,v 1.3 2019/04/23 18:13:11 schwarze Exp $
 .\" Copyright (c) 1999 Marc Espie <espie@openbsd.org>
 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
@@ -13,7 +13,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: May 13 2014 $
+.Dd $Mdocdate: April 23 2019 $
 .Dt OHASH_INIT 3
 .Os
 .Sh NAME
@@ -258,7 +258,7 @@ Multi-threaded applications should explicitly protect ohash table access.
 .%A Donald E. Knuth
 .%B The Art of Computer Programming
 .%V Vol. 3
-.%P pp 506-550
+.%P pp. 506\(en550
 .%D 1973
 .Re
 .Sh STANDARDS