Introducing explicit type for implicit digest component

Change-Id: Ib2cd9a986a6b8835b0217c10aba62dbb30fc8bbc
Refs: #2011
diff --git a/types.rst b/types.rst
index bc4ffa4..ddd39ec 100644
--- a/types.rst
+++ b/types.rst
@@ -19,6 +19,8 @@
 +---------------------------------------------+-------------------+----------------+
 | NameComponent                               | 8                 | 0x08           |
 +---------------------------------------------+-------------------+----------------+
+| ImplicitSha256DigestComponent               | 1                 | 0x01           |
++---------------------------------------------+-------------------+----------------+
 |                     **Interest packet**                                          |
 +---------------------------------------------+-------------------+----------------+
 | Selectors                                   | 9                 | 0x09           |