man-pages.7: tfix

Escape hyphen.

Signed-off-by: Jakub Wilk <jwilk@jwilk.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
diff --git a/man7/man-pages.7 b/man7/man-pages.7
index 654dd60..5204d6b 100644
--- a/man7/man-pages.7
+++ b/man7/man-pages.7
@@ -553,7 +553,7 @@
 .PP
 .in +4n
 .EX
-man 7 man-pages
+man 7 man\-pages
 .EE
 .in
 .PP