This README explains how to run pgindent, but it was written
for our former practice of running pgindent only infrequently.
Nowadays the plan is to keep the tree indent-clean all the time,
so the typical thing is to do an incremental pgindent run with
each commit. Revise to explain that as the normal case, and
the infrequent full-on process as a separate thing.
For now, pgperltidy is still a run-it-infrequently item.
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