getpwent_r.3: Change comment describing pw_gecos

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man3/getpwent_r.3

@@ -71,7 +71,7 @@ struct passwd {
     char    *pw_passwd;    /* user password */
     uid_t    pw_uid;       /* user ID */
     gid_t    pw_gid;       /* group ID */
-    char    *pw_gecos;     /* real name */
+    char    *pw_gecos;     /* user information */
     char    *pw_dir;       /* home directory */
     char    *pw_shell;     /* shell program */
 };