The term "Dungeons & Dragons" is not open content
The license states:
The text of the Open Gaming License itself is not Open Game Content. Instructions on using the License are provided within the License itself.
The following items are designated Product Identity, as defined in Section 1(e) of the Open Game License Version 1.0a, and are subject to the conditions set forth in Section 7 of the OGL, and are not Open Content: Dungeons & Dragons, D&D, Player’s Handbook, Dungeon Master,(...)
The text within the actual game rules in the SRD never uses the term "Dungeons and Dragons" so it is not part of the material made freely availably under the CC license.