Add coments to structure defn.

man5/utmp.5

@@ -53,6 +53,8 @@ around; details depend on the version of libc):
 .in +4n
 .nf
 .sp
+/* Values for ut_type field, below */
+
 #define UT_UNKNOWN      0
 #define RUN_LVL         1
 #define BOOT_TIME       2
@@ -68,7 +70,7 @@ around; details depend on the version of libc):
 #define UT_NAMESIZE      32
 #define UT_HOSTSIZE     256
 
-struct exit_status {
+struct exit_status {              /* Type for ut_exit, below */
     short int e_termination;      /* Process termination status */
     short int e_exit;             /* Process exit status */
 };