Add fio_generate_plots.1 man page from debian package

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/Makefile b/Makefile
index 8e439e6..99acec9 100644
--- a/Makefile
+++ b/Makefile
@@ -65,6 +65,7 @@
 	$(INSTALL) $(PROGS) $(SCRIPTS) $(DESTDIR)$(bindir)
 	$(INSTALL) -m 755 -d $(DESTDIR)$(mandir)/man1
 	$(INSTALL) -m 644 fio.1 $(DESTDIR)$(mandir)/man1
+	$(INSTALL) -m 644 fio_generate_plots.1 $(DESTDIR)$(mandir)/man1
 
 ifneq ($(wildcard .depend),)
 include .depend