Add AUTHORS and CONTRIBUTORS files like the official repos have.

AUTHORS

@@ -0,0 +1,9 @@
+# This is the official list of Bazel authors for copyright purposes.
+# This file is distinct from the CONTRIBUTORS files.
+# See the latter for an explanation.
+
+# Names should be added to this file as:
+# Name or Organization <email address>
+# The email address is not required for organizations.
+
+Tweag I/O Limited

CONTRIBUTORS

@@ -0,0 +1,13 @@
+# People who have agreed to one of the CLAs and can contribute patches.
+# The AUTHORS file lists the copyright holders; this file
+# lists people.  For example, Google employees are listed here
+# but not in AUTHORS, because Google holds the copyright.
+#
+# https://developers.google.com/open-source/cla/individual
+# https://developers.google.com/open-source/cla/corporate
+#
+# Names should be added to this file as:
+#     Name <email address>
+
+Mathieu Boespflug <[email protected]>
+Mateusz Kowalczyk <[email protected]>