add -s option to 'got ref' usage in man page
diff --git a/got/got.1 b/got/got.1
index a826de9..5051557 100644
--- a/got/got.1
+++ b/got/got.1
@@ -431,7 +431,7 @@ Recurse into sub-directories in the repository.
.It Cm tr
Short alias for
.Cm tree .
-.It Cm ref Oo Fl r Ar repository-path Oc Oo Fl l Oc Oo Fl d Ar name Oc Op Ar name Ar target
+.It Cm ref Oo Fl r Ar repository-path Oc Oo Fl l Oc Oo Fl d Ar name Oc Oo Fl s Oc Op Ar name Ar target
Manage references in a repository.
.Pp
If no options are passed, expect two arguments and attempt to create,