Doc: clarify the log message level of the VERBOSE option

Hi,

I'd like to clarify the log message level of the VERBOSE option
because I misunderstood that VACUUM VERBOSE messages cannot be
printed in the server log.

Although the hint is mentioned in "Table 19.2. Message Severity Levels",
it is not addressed for other commands.
> INFO	Provides information implicitly requested by the user, e.g., 
> output from VACUUM VERBOSE.
https://www.postgresql.org/docs/devel/runtime-config-logging.html#RUNTIME-CONFIG-SEVERITY-LEVELS

IIUC, the following SQL commands support the VERBOSE option:
* VACUUM
* ANALYZE
* REINDEX
* COPY
* EXPALIN

The VERBOSE option for EXPLAIN is not related to the log message level,
and COPY already specifies the log message level. Therefore, I'd like to
add descriptions for the VERBOSE option in the ANALYZE, VACUUM, and
REINDEX commands.

What do you think?

Regards,
-- 
Masahiro Ikeda
NTT DATA CORPORATION