encoding: update number assignments

This commit declares:

* TLV-TYPEs for typed name components in NDN naming conventions
* SignatureType number for HMAC
* ContentType numbers for Prefix Announcement and FLIC

This commit also:

* Improves stream insertion operator for SignatureTypeValue
* Adds stream insertion operator for ContentTypeValue
* Corrects several references to certificate format spec

refs #4577, #4649

Change-Id: Ibfd5cc1408cf892e38a2be93bf17e76f628f255d
diff --git a/src/security/v2/additional-description.hpp b/src/security/v2/additional-description.hpp
index 16281f9..4372807 100644
--- a/src/security/v2/additional-description.hpp
+++ b/src/security/v2/additional-description.hpp
@@ -33,7 +33,7 @@
 
 /**
  * @brief Abstraction of AdditionalDescription
- * @sa docs/tutorials/certificate-format.rst
+ * @sa docs/specs/certificate-format.rst
  */
 class AdditionalDescription
 {