Update a few URLs

Change-Id: Id7627a4452249dceed6e97514a1e28d37a1c6c96
diff --git a/AUTHORS.md b/AUTHORS.md
index a7af4a4..f494204 100644
--- a/AUTHORS.md
+++ b/AUTHORS.md
@@ -2,7 +2,7 @@
 
 The following lists maintainers, primary developers, and all much-appreciated contributors to NAC in alphabetical order.
 The specific contributions of individual authors can be obtained from the git history of the [official NAC repository](https://github.com/named-data/name-based-access-control).
-If you would like to become a contributor to the official repository, please follow the recommendations in <https://github.com/named-data/.github/blob/master/CONTRIBUTING.md>.
+If you would like to become a contributor to the official repository, please follow the recommendations in <https://github.com/named-data/.github/blob/main/CONTRIBUTING.md>.
 
 * ***(Maintainer)*** Alexander Afanaysev <https://users.cs.fiu.edu/~afanasyev>
 * Ashlesh Gawande <https://www.linkedin.com/in/agawande>
diff --git a/COPYING.md b/COPYING.md
index 760a0b4..bfc4cbe 100644
--- a/COPYING.md
+++ b/COPYING.md
@@ -1,10 +1,10 @@
-NAC library is licensed under the terms of the GNU Lesser General Public License,
+NAC is licensed under the terms of the GNU Lesser General Public License,
 version 3 or later.
 
-NAC library relies on third-party software, licensed under the following licenses:
+NAC relies on third-party software, licensed under the following licenses:
 
-- ndn-cxx library is licensed under the terms of the GNU Lesser General Public License,
-  version 3 or later.
+- ndn-cxx is licensed under the terms of the
+  [GNU Lesser General Public License version 3](https://github.com/named-data/ndn-cxx/blob/master/COPYING.md)
 
 - The Boost libraries are licensed under the
   [Boost Software License 1.0](https://www.boost.org/users/license.html)
@@ -12,9 +12,8 @@
 - The waf build system is licensed under the terms of the
   [BSD license](https://github.com/named-data/name-based-access-control/blob/new/waf)
 
-
 The LGPL and GPL licenses are provided below in this file.  For more information
-about these licenses, see https://www.gnu.org/licenses/
+about these licenses, see <https://www.gnu.org/licenses/>
 
 --------------------------------------------------------------------------------
 
diff --git a/README.md b/README.md
index f41b136..8064449 100644
--- a/README.md
+++ b/README.md
@@ -12,12 +12,11 @@
 ## Contributing
 
 We greatly appreciate contributions to the NAC code base, provided that they are
-licensed under the LGPL 3.0+ or a compatible license (see below).
-If you are new to the NDN software community, please read the
-[Contributor's Guide](https://github.com/named-data/.github/blob/master/CONTRIBUTING.md)
-to get started.
+licensed under the GNU LGPL version 3 or a compatible license.
+If you are new to the NDN software community, please read our [Contributor's Guide](
+https://github.com/named-data/.github/blob/main/CONTRIBUTING.md) to get started.
 
 ## License
 
-NAC is an open source project licensed under the LGPL version 3.
-See [`COPYING.md`](COPYING.md) for more information.
+NAC is free software distributed under the GNU Lesser General Public License version 3.
+See [`COPYING.md`](COPYING.md) for details.
diff --git a/docs/spec.rst b/docs/spec.rst
index bb706f3..038c141 100644
--- a/docs/spec.rst
+++ b/docs/spec.rst
@@ -44,7 +44,6 @@
      InitializationVector = INITIALIZATION-VECTOR-TYPE TLV-LENGTH *OCTET
      EncryptedPayloadKey = ENCRYPTED-PAYLOAD-KEY-TYPE TLV-LENGTH *OCTET
 
-
 Access Manager
 --------------
 
@@ -67,7 +66,6 @@
    KekContent = CONTENT-TYPE-TLV TLV-LENGTH
                 *OCTET ; = BER of public key /[access-namespace]/NAC/[dataset]/KEY/[key-id]
 
-
 Different versions of KDK are published, encrypted by the public key of the individual authorized member, following naming convention: ``/[access-namespace]/NAC/[dataset]/KDK/[key-id]/ENCRYPTED-BY/<authorized-member>/KEY/[member-key-id]``.  KDK is published in the following format:
 
 .. code-block:: abnf
@@ -83,7 +81,7 @@
 
 Within the ``EncryptedContent`` element,
 
-* ``EncryptedPayload`` contains `SafeBag <https://named-data.net/doc/ndn-cxx/0.7.1/specs/safe-bag.html>`__ of private key ``/[access-namespace]/NAC/[dataset]/KEY/[key-id]``
+* ``EncryptedPayload`` contains `SafeBag <https://docs.named-data.net/ndn-cxx/0.8.1/specs/safe-bag.html>`__ of private key ``/[access-namespace]/NAC/[dataset]/KEY/[key-id]``
 * ``EncryptedPayloadKey`` contains password for SafeBag, encrypted by public key ``/<authorized-member>/KEY/[member-key-id]``
 * ``InitializationVector`` and ``Name`` must be omitted
 
@@ -122,7 +120,6 @@
 * ``EncryptedPayload`` contains ContentKey encrypted by public key ``/[access-namespace]/NAC/[dataset]/KEK/[key-id]``
 * ``EncryptedPayloadKey``, ``InitializationVector``, and ``Name`` must be omitted
 
-
 Decryptor
 ---------
 
@@ -135,15 +132,15 @@
 TLV-TYPE number assignments
 ---------------------------
 
-+---------------------------------------------+------------------+-----------------+
-| Type                                        | Assigned number  | Assigned number |
-|                                             | (decimal)        | (hexadecimal)   |
-+=============================================+==================+=================+
-| EncryptedContent                            | 130              | 0x82            |
-+---------------------------------------------+------------------+-----------------+
-| EncryptedPayload                            | 132              | 0x84            |
-+---------------------------------------------+------------------+-----------------+
-| InitializationVector                        | 133              | 0x85            |
-+---------------------------------------------+------------------+-----------------+
-| EncryptedPayloadKey                         | 134              | 0x86            |
-+---------------------------------------------+------------------+-----------------+
++----------------------------------------+------------------+------------------+
+| Type                                   | Assigned number  | Assigned number  |
+|                                        | (decimal)        | (hexadecimal)    |
++========================================+==================+==================+
+| EncryptedContent                       | 130              | 0x82             |
++----------------------------------------+------------------+------------------+
+| EncryptedPayload                       | 132              | 0x84             |
++----------------------------------------+------------------+------------------+
+| InitializationVector                   | 133              | 0x85             |
++----------------------------------------+------------------+------------------+
+| EncryptedPayloadKey                    | 134              | 0x86             |
++----------------------------------------+------------------+------------------+