Update comment to reflect commit 1d41739e5a04b0e93304d24d864b6bfa3efc45f2.

Peter Geoghegan
Fix segmentation fault that an empty prepared statement could cause.

Back-patch to all supported branches.

Per bug #11335 from Haruka Takatsuka
doc: Remove dead link

The link to the NIST web page about DES standards leads to nowhere, and
according to archive.org has been forwarded to an unrelated page for
many years.  Therefore, just remove that link.  More up to date
information can be found via Wikipedia, for example.
Add tab-completion for reloptions like user_catalog_table.

Back-patch to 9.4 where user_catalog_table was added.

Review by Michael Paquier
Assorted message fixes and improvements
Rename C variables in formatting.c, for clarity

Also add C comments.  This should help future debugging of this
notorious file.