pgsql: doc: Group options in pg_amcheck reference page

doc: Group options in pg_amcheck reference page

The previous arrangement was just one big list, and the internal order
was not all consistent either.  Now arrange the options by group and
sort them, the way it's already done in the --help output and one
other reference pages.  Also fix some ordering in the --help output.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/cb3cffe694b6041c1de47b12b225e05f664c7285

Modified Files
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doc/src/sgml/ref/pg_amcheck.sgml | 451 ++++++++++++++++++++-------------------
src/bin/pg_amcheck/pg_amcheck.c  |   4 +-
2 files changed, 239 insertions(+), 216 deletions(-)