build: align minimum build dependencies with ndn-cxx

 * gcc 7.4
 * clang 6.0
 * Xcode 10.0 (11.3 or later recommended)

Change-Id: Ie867798d37898dbabb0620de719fff4bd46df590
diff --git a/docs/conf.py b/docs/conf.py
index 05d0f76..6c466d4 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -18,7 +18,7 @@
 # -- Project information -----------------------------------------------------
 
 project = u'ChronoSync: A Synchronization Protocol for NDN'
-copyright = u'Copyright © 2012-2021 Regents of the University of California.'
+copyright = u'Copyright © 2012-2022 Regents of the University of California.'
 author = u'Named Data Networking Project'
 
 # The short X.Y version.