to_timestamp docs

I don't think the changes made in PG 12 are documented accurately. It
currently says:

to_timestamp and to_date matches any single separator in the input
string or is skipped

However, I think it is more accurate to say _multiple_ whitespace can
also be matched by a single separator:

SELECT to_timestamp('%1976','_YYYY');
to_timestamp
------------------------
1976-01-01 00:00:00-05

SELECT to_timestamp('%%1976','_YYYY');
ERROR: invalid value "%197" for "YYYY"
DETAIL: Value must be an integer.

-- two spaces
--> SELECT to_timestamp(' 1976','_YYYY');
to_timestamp
------------------------
1976-01-01 00:00:00-05

--> SELECT to_timestamp(E'\t\t\t1976','_YYYY');
to_timestamp
------------------------
1976-01-01 00:00:00-05

Proposed patch attached.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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