Restore bisect_ppx-ocamlbuild to the docs
Restore bisect_ppx-ocamlbuild to the docs

Instructions mentioning the bisect_ppx-ocamlbuild package were
originally added in

  2008454de776246bac85d3467245259695658e6e

However, it took a while to release Bisect_ppx, and the new package, and
the instructions were confusing users in the meantime. They were
reverted by

  a22d372483a6d99a62c23b3dd29eaabf065932b0

In preparation for release, this commit restores the instructions.

[skip ci]

aantron/bisect_ppx,aantron/bisect_ppx