Corrections of minor misstatements in several papers on ECS manifolds

In the paper [3] the value of the invariant denoted by d and often called "rank" was misstated for a narrow class of examples of ECS manifolds: they were identified as having d = 1 instead of the correct value d = 2. The error was repeated, by citing [3], in [1], [2] and [4] -- [7]. We briefly describe the class in question, explain why it has d = 2, and list the required corrections of the affected papers.