[Rd] misspelling of "Mauchly" (PR#8908)

[g_lukas at freesurf.ch]

Hi there,

The word "Mauchly" is still misspelled as *"Mauchley", at least in 
some /output/ of mauchly.test() and in the SSD() help page.

Sincerely,
Lukas Giesinger