resolve_gitlink_ref(): improve docstring

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

refs.h

@@ -133,8 +133,12 @@ extern char *shorten_unambiguous_ref(const char *refname, int strict);
 /** rename ref, return 0 on success **/
 extern int rename_ref(const char *oldref, const char *newref, const char *logmsg);
 
-/** resolve ref in nested "gitlink" repository */
+/**
-extern int resolve_gitlink_ref(const char *name, const char *refname, unsigned char *sha1);
+ * Resolve refname in the nested "gitlink" repository that is located
+ * at path.  If the resolution is successful, return 0 and set sha1 to
+ * the name of the object; otherwise, return a non-zero value.
+ */
+extern int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1);
 
 /** lock a ref and then write its file */
 enum action_on_err { MSG_ON_ERR, DIE_ON_ERR, QUIET_ON_ERR };