docs: Extending documentation and manpages

Refs: #1462

Change-Id: If33a0f3c623daf3502ed301bcdc63892779463e3
diff --git a/docs/manpages/ndnsec-delete.rst b/docs/manpages/ndnsec-delete.rst
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+ndnsec-delete
+=============
+
+``ndnsec-delete`` is a tool to delete security data from both **Public Info Base** and
+**Trusted Platform Module**.
+
+Usage
+-----
+
+::
+
+    ndnsec-delete [-h] [-kc] name
+
+Description
+-----------
+
+By default, ``ndnsec-delete`` interpret ``name`` as an identity name. If an identity is deleted,
+all the keys and certificates belonging to the identity will be deleted as well. If a key is
+deleted,  all the certificate belonging to the key will be deleted as well.
+
+Options
+-------
+
+``-k``
+  Interpret ``name`` as a key name and delete the key and its related data.
+
+``-c``
+  Interpret ``name`` as a certificate name and delete the certificate.
+
+Examples
+--------
+
+Delete all data related to an identity:
+
+::
+
+    $ ndnsec-delete /ndn/test/david