pylintrc: add explicit Apache license for export #637

Most content in the external styleguide repo is Creative Commons based,
so add an explicit license to files that aren't to avoid confusion.

pylintrc

@@ -5,6 +5,20 @@
 # Its canonical open-source location is:
 #   https://google.github.io/styleguide/pylintrc
 
+# Copyright 2018 Google LLC
+#
+# 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.
+
 [MAIN]
 
 # Files or directories to be skipped. They should be base names, not paths.