pgsql: Add missing pg_description strings for pg_type entries.

Add missing pg_description strings for pg_type entries.

I noticed that all non-composite, non-array entries in pg_type.dat
had descr strings, except for "json" and the pseudo-types. The
lack for json seems certainly an oversight, and there's surely
little reason to not have entries for the pseudo-types either.
So add some.

"make reformat-dat-files" turned up some formatting issues in
pg_amop.dat, too, so fix those in passing.

No catversion bump since the backend doesn't care too much what is
in pg_description.

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/b09a64d602a19c9a3cc69e4bb0f8986a6f5facf4

Modified Files
--------------
src/include/catalog/pg_amop.dat | 12 ++++++------
src/include/catalog/pg_type.dat | 28 +++++++++++++++++++---------
src/tools/pgindent/README | 6 ++++++
3 files changed, 31 insertions(+), 15 deletions(-)