Add ruby-module(5) to SEE ALSO of port-modules(5)

Whereas the text of port-modules(5) tells us to see the ruby-module(5) page
for information on the lang/ruby module, let's add ruby-module(5) to the
list of SEE ALSO at the end of port-modules(5).

ok?

--Kurt

Index: port-modules.5
===================================================================
RCS file: /cvs/src/share/man/man5/port-modules.5,v
retrieving revision 1.246
diff -u -p -r1.246 port-modules.5
--- port-modules.5 15 Sep 2020 10:03:09 -0000 1.246
+++ port-modules.5 29 Sep 2020 19:09:36 -0000
@@ -2036,4 +2036,5 @@ One of the latter has to be provided by
.Sh SEE ALSO
.Xr make 1 ,
.Xr bsd.port.mk 5 ,
+.Xr ruby-module 5 ,
.Xr ports 7