Fix build with sphinxcontrib-bibtex 2.0 and later

Also fix typo in changelog

Change-Id: I088292fc12ae8c182a00bbb2a6732154105e60b7
diff --git a/changelog.rst b/changelog.rst
index ba86ec2..bba8cce 100644
--- a/changelog.rst
+++ b/changelog.rst
@@ -6,7 +6,7 @@
 
 - Rewrite TLV syntax specifications using `IETF Augmented BNF (RFC 5234) <https://tools.ietf.org/html/rfc5234>`__
 
-  + Require shortest encoding for TLV-TYPE and TLV-LENGTH numbers
+- Require shortest encoding for TLV-TYPE and TLV-LENGTH numbers
 
 - **Interest**
 
@@ -25,8 +25,8 @@
 
 - **Name**
 
-  + Lift restriction on name component types, allowing types in the range ``1`` - ``32767``
-  + Correct definition of name URI encoding: disallow unescaped encoding of PLUS ``+`` and allow TILDE ``~``
+  + Lift restriction on name component types, allowing types in the range 1-65535
+  + Correct definition of name URI encoding: disallow unescaped encoding of PLUS (``+``) and allow TILDE (``~``)
   + Add well-known special-use component types:
 
     - ``ParametersSha256DigestComponent`` (type 2)
diff --git a/conf.py b/conf.py
index 324955e..c6e587c 100644
--- a/conf.py
+++ b/conf.py
@@ -18,7 +18,7 @@
 # -- Project information -----------------------------------------------------
 
 project = 'NDN Packet Format Specification'
-copyright = '2013-2020, Named Data Networking Project'
+copyright = '2013-2021, Named Data Networking Project'
 
 # The short X.Y version.
 version = '0.3'
@@ -31,7 +31,7 @@
 
 # If your documentation needs a minimal Sphinx version, state it here.
 #
-needs_sphinx = '1.3'
+needs_sphinx = '2.1'
 
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
@@ -52,6 +52,8 @@
 # This pattern also affects html_static_path and html_extra_path.
 exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
 
+bibtex_bibfiles = ['refs.bib']
+
 
 # -- Options for HTML output -------------------------------------------------
 
diff --git a/ndnspec-refs.bib b/refs.bib
similarity index 100%
rename from ndnspec-refs.bib
rename to refs.bib
diff --git a/signature.rst b/signature.rst
index 0d2d712..56c49ff 100644
--- a/signature.rst
+++ b/signature.rst
@@ -276,4 +276,4 @@
 The shared key used to generate the HMAC signature can be identified by the :ref:`KeyLocator` element, e.g., by using the ``Name`` according to the application's naming conventions.
 It is the application's responsibility to associate the shared key with the identities of the parties who hold the shared key.
 
-.. bibliography:: ndnspec-refs.bib
+.. bibliography::