docs: delete certificate spec
Moved to the NDN-packet-spec repo
https://github.com/named-data/NDN-packet-spec/commit/3a74e134979606af9a2b90b12f141f8794ad96d7
Change-Id: I57aec08aeb553d5eb6c5a7c368ba03b904b1e4ed
diff --git a/docs/specs/safe-bag.rst b/docs/specs/safe-bag.rst
index 04e3c4e..b4ae80a 100644
--- a/docs/specs/safe-bag.rst
+++ b/docs/specs/safe-bag.rst
@@ -1,15 +1,14 @@
SafeBag Format for Exported Credentials
=======================================
-Sometimes it may be necessary to export an identity's credentials (i.e., private key and
-associated certificate) from one machine and import them into another. This requires a
-secure container to carry the sensitive information. We define **SafeBag**, which contains
-an :doc:`NDN certificate </specs/certificate>` and the corresponding private key in encrypted
-form. The private key is formatted as a DER-encoded
-`EncryptedPrivateKeyInfo <https://datatracker.ietf.org/doc/html/rfc5208#section-6>`__
-structure as described in PKCS #8.
+Sometimes it may be necessary to export an identity's credentials (i.e., private key and associated
+certificate) from one machine and import them into another. This requires a secure container to
+carry the sensitive information. For this purpose, we define the **SafeBag** format, which contains
+an `NDN certificate <https://named-data.net/doc/NDN-packet-spec/0.3/certificate.html>`__ and the
+corresponding private key in encrypted form. The private key is formatted as a DER-encoded
+:rfc:`EncryptedPrivateKeyInfo <5208#section-6>` structure as described in PKCS #8.
-The TLV-based format of ``SafeBag`` is defined as follows:
+The TLV encoding of ``SafeBag`` is defined as follows:
.. code-block:: abnf