Some sections of the documentation used "exclusive lock" to describe
that an ACCESS EXCLUSIVE lock is taken during a given operation.  This
can be confusing to the reader as ACCESS SHARE is allowed with an
EXCLUSIVE lock is used, but that would not be the case with what is
described on those parts of the documentation.

Author: Greg Rychlewski
Discussion: https://postgr.es/m/CAKemG7VptD=7fNWckFMsMVZL_zzvgDO6v2yVmQ+ZiBfc_06kCQ@mail.gmail.com
Backpatch-through: 9.6