Update copyright headers and years

shell.c

@@ -1,20 +1,11 @@
 /*
+    SPDX-License-Identifier: GPL-2.0-or-later
+
     UMKa - User-Mode KolibriOS developer tools
-    umka_shell - interactive shell
-    Copyright (C) 2018--2020  Ivan Baravy <dunkaist@gmail.com>
+    umka_shell - the shell
 
-    This program is free software: you can redistribute it and/or modify
-    it under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 2 of the License, or
-    (at your option) any later version.
-
-    This program is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+    Copyright (C) 2017-2022  Ivan Baravy <dunkaist@gmail.com>
+    Copyright (C) 2021  Magomed Kostoev <mkostoevr@yandex.ru>
 */
 
 #include <stdio.h>