update to latest documentation and update copyright year
diff --git a/coders/webp.c b/coders/webp.c
index 421528f..16d8d30 100644
--- a/coders/webp.c
+++ b/coders/webp.c
@@ -17,7 +17,7 @@
% March 2011 %
% %
% %
-% Copyright 1999-2020 ImageMagick Studio LLC, a non-profit organization %
+% Copyright 1999-2021 ImageMagick Studio LLC, a non-profit organization %
% dedicated to making software imaging solutions freely available. %
% %
% You may not use this file except in compliance with the License. You may %
