pgsql: Improve pgindent release workflow.

Improve pgindent release workflow.

Update RELEASE_CHANGES to direct the reader towards completing the steps
outlined in the pgindent README, both as a pre-beta task and as a task
to be performed when starting a new development cycle.

This makes it less likely that somebody will miss updating the
.git-blame-ignore-revs file when running pgindent against the tree as a
routine release change task.

Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CAH2-Wz=2PjF4As8dWECArsXxLKganYmQ-s0UeGqHHbHhqDKqeA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/bc49ab3c277b6b478bdad80c1ae36f926a33b4a6

Modified Files
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src/tools/RELEASE_CHANGES | 8 ++------
src/tools/pgindent/README | 3 ++-
2 files changed, 4 insertions(+), 7 deletions(-)