[App] Add copyright notice to most significant java files

Author: ViliusSutkus89

application/app/src/main/java/com/viliussutkus89/android/pdf2htmlex/application/ConverterActivity.java

@@ -1,3 +1,22 @@
+/*
+ * ConverterActivity.java
+ *
+ * Copyright (C) 2021 Vilius Sutkus'89
+ *
+ * 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/>.
+ */
+
 package com.viliussutkus89.android.pdf2htmlex.application;
 
 import android.content.Intent;

application/app/src/main/java/com/viliussutkus89/android/pdf2htmlex/application/ConverterWorker.java

@@ -1,3 +1,22 @@
+/*
+ * ConverterWorker.java
+ *
+ * Copyright (C) 2021 Vilius Sutkus'89
+ *
+ * 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/>.
+ */
+
 package com.viliussutkus89.android.pdf2htmlex.application;
 
 import android.content.ContentResolver;