added NamedQid and GridQid to the qudit concept page (#3338)
added NamedQid and GridQid to the qudit concept page (#3338)

Adds NamedQid and GridQid to the qudit concept page.
balopat/Cirq,quantumlib/Cirq,balopat/Cirq,quantumlib/Cirq,balopat/Cirq,quantumlib/Cirq,quantumlib/Cirq,quantumlib/Cirq