add GPL license and header comments

src/settings.rs

@@ -1,3 +1,25 @@
+/*
+ * Copyright 2023 Trevor Bentley
+ *
+ * Author: Trevor Bentley
+ * Contact: gitsy@@trevorbentley.com
+ * Source: https://github.com/mrmekon/itsy-gitsy
+ *
+ * This file is part of Itsy-Gitsy.
+ *
+ * Itsy-Gitsy 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.
+ *
+ * Itsy-Gitsy 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 Itsy-Gitsy.  If not, see <http://www.gnu.org/licenses/>.
+ */
 use crate::error;
 use crate::git::{GitFile, GitObject, GitRepo};
 use clap::Parser;