Add copyright notice to LICENSE

LICENSE

@@ -1,3 +1,22 @@
+Soif - An application to monitor and display soil moisture content for drip 
+irrigation.
+    Copyright (C) 2019, 2020 Anurag Roy, Aritra Roy Gosthipaty
+
+    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/>.                    
+
+=============================================================================
+
                     GNU GENERAL PUBLIC LICENSE
                        Version 3, 29 June 2007