libmsc/msc_vty.c: fix documentation of 'show subscriber id'

Change-Id: I3357e71ae54e22b97cbb3707712445d7602c1129
diff --git a/src/libmsc/msc_vty.c b/src/libmsc/msc_vty.c
index 67955d3..8cce7a0 100644
--- a/src/libmsc/msc_vty.c
+++ b/src/libmsc/msc_vty.c
@@ -960,7 +960,7 @@
 	"Legacy alias for 'msisdn'\n"		\
 	"Identify subscriber by IMSI\n"					\
 	"Identify subscriber by TMSI\n"					\
-	"Identify subscriber by database ID\n"				\
+	"Legacy alias for 'imsi'\n"					\
 	"Identifier for the subscriber\n"
 
 DEFUN(show_subscr,