build: align minimum build dependencies with ndn-cxx

 * boost 1.65.1
 * gcc 7.4
 * clang 6.0
 * Xcode 10.0 (11.3 or later recommended)

Change-Id: I5e41f2a70d6c510dcb889a083a51504121b4627d
diff --git a/docs/conf.py b/docs/conf.py
index 92bf794..e661298 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -18,7 +18,7 @@
 # -- Project information -----------------------------------------------------
 
 project = u'Named Data Networking Forwarding Daemon (NFD)'
-copyright = u'Copyright © 2014-2021 Named Data Networking Project.'
+copyright = u'Copyright © 2014-2022 Named Data Networking Project.'
 author = u'Named Data Networking Project'
 
 # The short X.Y version.