Add copyright notices

youtubeUnblock becames bigger and copyright notices in each file will
make it easier for anyone to do something over it.

src/quic.c

@@ -1,3 +1,22 @@
+/*
+  youtubeUnblock - https://github.com/Waujito/youtubeUnblock
+
+  Copyright (C) 2024-2025 Vadim Vetrov <vetrovvd@gmail.com>
+
+  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 3 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/>.
+*/
+
 #include "quic.h"
 #include "tls.h"
 #include "logging.h"