RootishArrayStack Space usage subsection

[deepindeed2022]

There is a question about ods-cpp 2.6.2 Space Usage " The number of blocks r, used by a RootishArrayStack that stores n elements therefore satisfies (r − 2)(r − 1) ≤ n " . I think n should satisfies (r-2)(r-1)/2 ≤ n. And the following proof process should be changed correspondingly.

[patmorin]

Thanks. I've just pushed the fix.