* master:
  lib/zodb: Fix typos
  lib/zodb: Try to clarify zconn_at intent
  bigfile/bench_1filezodb: Fix thinko when importing pygolang

It is hard for people to understand current wording, so let's expand
zconn_at description to additionally explain what it is providing with
second set of words, which, hopefully, lowers potential ambiguity a bit.

/reported-by @jwolf083