submodule.c: describe submodule_to_gitdir() in a new comment

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Han-Wen Nienhuys committed Sep 25, 2017 at 17:59 UTC 3ce08548bb8768259c98f7fcf30be4c0bae9c611
1 file changed +4
submodule.c
+4
@@ -1997,6 +1997,10 @@ const char *get_superproject_working_tree(void)
1997 return ret;
1998 }
1999
2000 +/*
2001 + * Put the gitdir for a submodule (given relative to the main
2002 + * repository worktree) into `buf`, or return -1 on error.
2003 + */
2004 int submodule_to_gitdir(struct strbuf *buf, const char *submodule)
2005 {
2006 const struct submodule *sub;