Update copyright year in built documentation

We've made changes to documentation this year, but neglected to
update the copyright year in the footer of built docs, so do that
now.

diff --git a/doc/source/conf.py b/doc/source/conf.py
index 61d1276..e32f00d 100755 (executable)
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2018-2020 mudpy authors. Permission to use, copy,
+# Copyright (c) 2018-2021 mudpy authors. Permission to use, copy,
 # modify, and distribute this software is granted under terms
 # provided in the LICENSE file distributed with this software.
 
@@ -12,7 +12,7 @@ project = 'mudpy'
 
 add_function_parentheses = True
 add_module_names = True
-copyright = '2004-2020, mudpy authors'
+copyright = '2004-2021, mudpy authors'
 extensions = ['sphinx.ext.autodoc']
 html_favicon = '_static/logo.svg'
 html_logo = '_static/logo.svg'