added license language

Makefile

@@ -1,3 +1,18 @@
+# Solvedle wordle dictionary solver Copyright © 2022 Nicholas Hope
+#
+# Available at https://git.paco.to/nick/wordle-algorithm
+#
+# 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/>.
 printing ?= 0
 
 .PHONY: default