man: use "search for unit"

man: use "search for unit"

To "search something", in the meaning of looking for it, is valid,
but "search _for_ something" is much more commonly used, especially when
the meaning could be confused with "looking _through_ something"
(for some other object).

(C.f. "the police search a person", "the police search for a person".)

Also reword the rest of the paragraph to avoid using "automatically"
three times.