Fix copyright notice on Makefile + bump stable version.

ueforth/Makefile

@@ -1,3 +1,17 @@
+# Copyright 2021 Bradley D. Nelson
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 VERSION=7.0.6.2
 REVISION=$(shell git rev-parse HEAD)
 REVSHORT=$(shell echo $(REVISION) | head -c 7)