A computing or networking architecture suggested by the marketing department for sales purposes rather than for technical reasons. Cisco calls them "reference designs".
The oldest mention of "markitecture" I can find dates back from 1990 :
CA 90s was characterized as a "markitecture" by Jeff Schulman, vice president and analyst with the Gartner Group, Stamford, Conn. "It is a marketing architecture, a statement of direction. It does not specify when products will be delivered, or which products will map to the architecture. It does not help users in a specific sense, only in a general sense".